Sleep Disorders: Conditions characterized by disturbances of usual sleep patterns or behaviors. Sleep disorders may be divided into three major categories: DYSSOMNIAS (i.e. disorders characterized by insomnia or hypersomnia), PARASOMNIAS (abnormal sleep behaviors), and sleep disorders secondary to medical or psychiatric disorders. (From Thorpy, Sleep Disorders Medicine, 1994, p187)Sleep: A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility.Sleep Disorders, Circadian Rhythm: Dyssomnias associated with disruption of the normal 24 hour sleep wake cycle secondary to travel (e.g., JET LAG SYNDROME), shift work, or other causes.Sleep, REM: A stage of sleep characterized by rapid movements of the eye and low voltage fast pattern EEG. It is usually associated with dreaming.Parasomnias: Movements or behaviors associated with sleep, sleep stages, or partial arousals from sleep that may impair sleep maintenance. Parasomnias are generally divided into four groups: arousal disorders, sleep-wake transition disorders, parasomnias of REM sleep, and nonspecific parasomnias. (From Thorpy, Sleep Disorders Medicine, 1994, p191)Narcolepsy: A condition characterized by recurrent episodes of daytime somnolence and lapses in consciousness (microsomnias) that may be associated with automatic behaviors and AMNESIA. CATAPLEXY; SLEEP PARALYSIS, and hypnagogic HALLUCINATIONS frequently accompany narcolepsy. The pathophysiology of this disorder includes sleep-onset rapid eye movement (REM) sleep, which normally follows stage III or IV sleep. (From Neurology 1998 Feb;50(2 Suppl 1):S2-S7)Sleep Initiation and Maintenance Disorders: Disorders characterized by impairment of the ability to initiate or maintain sleep. This may occur as a primary disorder or in association with another medical or psychiatric condition.Sleep Disorders, Intrinsic: Dyssomnias (i.e., insomnias or hypersomnias) associated with dysfunction of internal sleep mechanisms or secondary to a sleep-related medical disorder (e.g., sleep apnea, post-traumatic sleep disorders, etc.). (From Thorpy, Sleep Disorders Medicine, 1994, p187)Polysomnography: Simultaneous and continuous monitoring of several parameters during sleep to study normal and abnormal sleep. The study includes monitoring of brain waves, to assess sleep stages, and other physiological variables such as breathing, eye movements, and blood oxygen levels which exhibit a disrupted pattern with sleep disturbances.Sleep Apnea, Obstructive: A disorder characterized by recurrent apneas during sleep despite persistent respiratory efforts. It is due to upper airway obstruction. The respiratory pauses may induce HYPERCAPNIA or HYPOXIA. Cardiac arrhythmias and elevation of systemic and pulmonary arterial pressures may occur. Frequent partial arousals occur throughout sleep, resulting in relative SLEEP DEPRIVATION and daytime tiredness. Associated conditions include OBESITY; ACROMEGALY; MYXEDEMA; micrognathia; MYOTONIC DYSTROPHY; adenotonsilar dystrophy; and NEUROMUSCULAR DISEASES. (From Adams et al., Principles of Neurology, 6th ed, p395)Sleep Apnea Syndromes: Disorders characterized by multiple cessations of respirations during sleep that induce partial arousals and interfere with the maintenance of sleep. Sleep apnea syndromes are divided into central (see SLEEP APNEA, CENTRAL), obstructive (see SLEEP APNEA, OBSTRUCTIVE), and mixed central-obstructive types.Nocturnal Myoclonus Syndrome: Excessive periodic leg movements during sleep that cause micro-arousals and interfere with the maintenance of sleep. This condition induces a state of relative sleep deprivation which manifests as excessive daytime hypersomnolence. The movements are characterized by repetitive contractions of the tibialis anterior muscle, extension of the toe, and intermittent flexion of the hip, knee and ankle. (Adams et al., Principles of Neurology, 6th ed, p387)Disorders of Excessive Somnolence: Disorders characterized by hypersomnolence during normal waking hours that may impair cognitive functioning. Subtypes include primary hypersomnia disorders (e.g., IDIOPATHIC HYPERSOMNOLENCE; NARCOLEPSY; and KLEINE-LEVIN SYNDROME) and secondary hypersomnia disorders where excessive somnolence can be attributed to a known cause (e.g., drug affect, MENTAL DISORDERS, and SLEEP APNEA SYNDROME). (From J Neurol Sci 1998 Jan 8;153(2):192-202; Thorpy, Principles and Practice of Sleep Medicine, 2nd ed, p320)Restless Legs Syndrome: A disorder characterized by aching or burning sensations in the lower and rarely the upper extremities that occur prior to sleep or may awaken the patient from sleep.Wakefulness: A state in which there is an enhanced potential for sensitivity and an efficient responsiveness to external stimuli.Somnambulism: A parasomnia characterized by a partial arousal that occurs during stage IV of non-REM sleep. Affected individuals exhibit semipurposeful behaviors such as ambulation and are difficult to fully awaken. Children are primarily affected, with a peak age range of 4-6 years.Chronobiology Disorders: Disruptions of the rhythmic cycle of bodily functions or activities.Jet Lag Syndrome: A chronobiologic disorder resulting from rapid travel across a number of time zones, characterized by insomnia or hypersomnolence, fatigue, behavioral symptoms, headaches, and gastrointestinal disturbances. (From Cooper, Sleep, 1994, pp593-8)Sleep Stages: Periods of sleep manifested by changes in EEG activity and certain behavioral correlates; includes Stage 1: sleep onset, drowsy sleep; Stage 2: light sleep; Stages 3 and 4: delta sleep, light sleep, deep sleep, telencephalic sleep.Melatonin: A biogenic amine that is found in animals and plants. In mammals, melatonin is produced by the PINEAL GLAND. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of SLEEP, mood, and REPRODUCTION. Melatonin is also an effective antioxidant.Circadian Rhythm: The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs and stimuli, hormone secretion, sleeping, and feeding.Cataplexy: A condition characterized by transient weakness or paralysis of somatic musculature triggered by an emotional stimulus or physical exertion. Cataplexy is frequently associated with NARCOLEPSY. During a cataplectic attack, there is a marked reduction in muscle tone similar to the normal physiologic hypotonia that accompanies rapid eye movement sleep (SLEEP, REM). (From Adams et al., Principles of Neurology, 6th ed, p396)REM Sleep Behavior Disorder: A disorder characterized by episodes of vigorous and often violent motor activity during REM sleep (SLEEP, REM). The affected individual may inflict self injury or harm others, and is difficult to awaken from this condition. Episodes are usually followed by a vivid recollection of a dream that is consistent with the aggressive behavior. This condition primarily affects adult males. (From Adams et al., Principles of Neurology, 6th ed, p393)Sleep Medicine Specialty: A medical specialty concerned with the diagnosis and treatment of SLEEP WAKE DISORDERS and their causes.Sleep Bruxism: A sleep disorder characterized by grinding and clenching of the teeth and forceful lateral or protrusive jaw movements. Sleep bruxism may be associated with TOOTH INJURIES; TEMPOROMANDIBULAR JOINT DISORDERS; sleep disturbances; and other conditions.Dyssomnias: A broad category of sleep disorders characterized by either hypersomnolence or insomnia. The three major subcategories include intrinsic (i.e., arising from within the body) (SLEEP DISORDERS, INTRINSIC), extrinsic (secondary to environmental conditions or various pathologic conditions), and disturbances of circadian rhythm. (From Thorpy, Sleep Disorders Medicine, 1994, p187)Mental Disorders: Psychiatric illness or diseases manifested by breakdowns in the adaptational process expressed primarily as abnormalities of thought, feeling, and behavior producing either distress or impairment of function.Arousal: Cortical vigilance or readiness of tone, presumed to be in response to sensory stimulation via the reticular activating system.Bipolar Disorder: A major affective disorder marked by severe mood swings (manic or major depressive episodes) and a tendency to remission and recurrence.Snoring: Rough, noisy breathing during sleep, due to vibration of the uvula and soft palate.Electroencephalography: Recording of electric currents developed in the brain by means of electrodes applied to the scalp, to the surface of the brain, or placed within the substance of the brain.Bender-Gestalt Test: A psychological test consisting of nine geometric designs on cards. The subject is asked to redraw them from memory after each one is presented individually.Actigraphy: The measurement and recording of MOTOR ACTIVITY to assess rest/activity cycles.Phototherapy: Treatment of disease by exposure to light, especially by variously concentrated light rays or specific wavelengths.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Hypersomnolence, Idiopathic: A sleep disorder of central nervous system origin characterized by prolonged nocturnal sleep and periods of daytime drowsiness. Affected individuals experience difficulty with awakening in the morning and may have associated sleep drunkenness, automatic behaviors, and memory disturbances. This condition differs from narcolepsy in that daytime sleep periods are longer, there is no association with CATAPLEXY, and the multiple sleep latency onset test does not record sleep-onset rapid eye movement sleep. (From Chokroverty, Sleep Disorders Medicine, 1994, pp319-20; Psychiatry Clin Neurosci 1998 Apr:52(2):125-129)Sleep Arousal Disorders: Sleep disorders characterized by impaired arousal from the deeper stages of sleep (generally stage III or IV sleep).Night Terrors: A disorder characterized by incomplete arousals from sleep associated with behavior suggesting extreme fright. This condition primarily affects children and young adults and the individual generally has no recall of the event. Episodes tend to occur during stage III or IV. SOMNAMBULISM is frequently associated with this condition. (Adams et al., Principles of Neurology, 6th ed, p391)Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.Anxiety Disorders: Persistent and disabling ANXIETY.Mood Disorders: Those disorders that have a disturbance in mood as their predominant feature.Hypnotics and Sedatives: Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety.Comorbidity: The presence of co-existing or additional diseases with reference to an initial diagnosis or with reference to the index condition that is the subject of study. Comorbidity may affect the ability of affected individuals to function and also their survival; it may be used as a prognostic indicator for length of hospital stay, cost factors, and outcome or survival.Nocturia: Frequent URINATION at night that interrupts sleep. It is often associated with outflow obstruction, DIABETES MELLITUS, or bladder inflammation (CYSTITIS).Sleep Deprivation: The state of being deprived of sleep under experimental conditions, due to life events, or from a wide variety of pathophysiologic causes such as medication effect, chronic illness, psychiatric illness, or sleep disorder.Electrooculography: Recording of the average amplitude of the resting potential arising between the cornea and the retina in light and dark adaptation as the eyes turn a standard distance to the right and the left. The increase in potential with light adaptation is used to evaluate the condition of the retinal pigment epithelium.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Fatigue: The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli.Dreams: A series of thoughts, images, or emotions occurring during sleep which are dissociated from the usual stream of consciousness of the waking state.Sleep Paralysis: A common condition characterized by transient partial or total paralysis of skeletal muscles and areflexia that occurs upon awakening from sleep or less often while falling asleep. Stimuli such as touch or sound may terminate the episode, which usually has a duration of seconds to minutes. This condition may occur in normal subjects or be associated with NARCOLEPSY; CATAPLEXY; and hypnagogic HALLUCINATIONS. The pathophysiology of this condition is closely related to the normal hypotonia that occur during REM sleep. (From Adv Neurol 1995;67:245-271)Kleine-Levin Syndrome: A rare condition characterized by recurrent hypersomnias associated with hyperphagia, occurring primarily in males in the second to third decade of life. Clinical features include mental confusion, excessive sleep requirements (approximately 18 hours per day), restlessness, and in some cases hallucinations. Episodes have a duration of days to weeks, and may recur several times per year. This condition may resolve spontaneously over several years. (From Adams, et al., Principles of Neurology, 6th ed, p569)Bruxism: A disorder characterized by grinding and clenching of the teeth.Diagnostic and Statistical Manual of Mental Disorders: Categorical classification of MENTAL DISORDERS based on criteria sets with defining features. It is produced by the American Psychiatric Association. (DSM-IV, page xxii)Depressive Disorder: An affective disorder manifested by either a dysphoric mood or loss of interest or pleasure in usual activities. The mood disturbance is prominent and relatively persistent.Hyperacusis: An abnormally disproportionate increase in the sensation of loudness in response to auditory stimuli of normal volume. COCHLEAR DISEASES; VESTIBULOCOCHLEAR NERVE DISEASES; FACIAL NERVE DISEASES; STAPES SURGERY; and other disorders may be associated with this condition.Continuous Positive Airway Pressure: A technique of respiratory therapy, in either spontaneously breathing or mechanically ventilated patients, in which airway pressure is maintained above atmospheric pressure throughout the respiratory cycle by pressurization of the ventilatory circuit. (On-Line Medical Dictionary [Internet]. Newcastle upon Tyne(UK): The University Dept. of Medical Oncology: The CancerWEB Project; c1997-2003 [cited 2003 Apr 17]. Available from: http://cancerweb.ncl.ac.uk/omd/)Habits: Acquired or learned responses which are regularly manifested.Orexin Receptors: G-protein-coupled NEUROPEPTIDE RECEPTORS that have specificity for OREXINS and play a role in appetite control, and sleep-wake cycles. Two principle receptor types exist, each having a specificity for OREXIN A and OREXIN B peptide subtypes.Cross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Depressive Disorder, Major: Marked depression appearing in the involution period and characterized by hallucinations, delusions, paranoia, and agitation.Secobarbital: A barbiturate that is used as a sedative. Secobarbital is reported to have no anti-anxiety activity.Depression: Depressive states usually of moderate intensity in contrast with major depression present in neurotic and psychotic disorders.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Neuropeptides: Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells.Attention Deficit Disorder with Hyperactivity: A behavior disorder originating in childhood in which the essential features are signs of developmentally inappropriate inattention, impulsivity, and hyperactivity. Although most individuals have symptoms of both inattention and hyperactivity-impulsivity, one or the other pattern may be predominant. The disorder is more frequent in males than females. Onset is in childhood. Symptoms often attenuate during late adolescence although a minority experience the full complement of symptoms into mid-adulthood. (From DSM-V)Rhinomanometry: Technique for measuring air pressure and the rate of airflow in the nasal cavity during respiration.Hemodialysis Units, Hospital: Hospital units in which care is provided the hemodialysis patient. This includes hemodialysis centers in hospitals.Mandibular Advancement: Moving a retruded mandible forward to a normal position. It is commonly performed for malocclusion and retrognathia. (From Jablonski's Dictionary of Dentistry, 1992)Trazodone: A serotonin uptake inhibitor that is used as an antidepressive agent. It has been shown to be effective in patients with major depressive disorders and other subsets of depressive disorders. It is generally more useful in depressive disorders associated with insomnia and anxiety. This drug does not aggravate psychotic symptoms in patients with schizophrenia or schizoaffective disorders. (From AMA Drug Evaluations Annual, 1994, p309)Receptors, Neuropeptide: Cell surface receptors that bind specific neuropeptides with high affinity and trigger intracellular changes influencing the behavior of cells. Many neuropeptides are also hormones outside of the nervous system.Hydroxyzine: A histamine H1 receptor antagonist that is effective in the treatment of chronic urticaria, dermatitis, and histamine-mediated pruritus. Unlike its major metabolite CETIRIZINE, it does cause drowsiness. It is also effective as an antiemetic, for relief of anxiety and tension, and as a sedative.Psychology, Clinical: The branch of psychology concerned with psychological methods of recognizing and treating behavior disorders.Sleep Apnea, Central: A condition associated with multiple episodes of sleep apnea which are distinguished from obstructive sleep apnea (SLEEP APNEA, OBSTRUCTIVE) by the complete cessation of efforts to breathe. This disorder is associated with dysfunction of central nervous system centers that regulate respiration.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Quality of Life: A generic concept reflecting concern with the modification and enhancement of life attributes, e.g., physical, political, moral and social environment; the overall condition of a human life.Psychiatric Status Rating Scales: Standardized procedures utilizing rating scales or interview schedules carried out by health personnel for evaluating the degree of mental illness.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Cognition Disorders: Disturbances in mental processes related to learning, thinking, reasoning, and judgment.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Tonsillectomy: Surgical removal of a tonsil or tonsils. (Dorland, 28th ed)Stress Disorders, Post-Traumatic: A class of traumatic stress disorders with symptoms that last more than one month. There are various forms of post-traumatic stress disorder, depending on the time of onset and the duration of these stress symptoms. In the acute form, the duration of the symptoms is between 1 to 3 months. In the chronic form, symptoms last more than 3 months. With delayed onset, symptoms develop more than 6 months after the traumatic event.Central Nervous System Stimulants: A loosely defined group of drugs that tend to increase behavioral alertness, agitation, or excitation. They work by a variety of mechanisms, but usually not by direct excitation of neurons. The many drugs that have such actions as side effects to their main therapeutic use are not included here.Enuresis: Involuntary discharge of URINE after expected age of completed development of urinary control. This can happen during the daytime (DIURNAL ENURESIS) while one is awake or during sleep (NOCTURNAL ENURESIS). Enuresis can be in children or in adults (as persistent primary enuresis and secondary adult-onset enuresis).Parkinson Disease: A progressive, degenerative neurologic disease characterized by a TREMOR that is maximal at rest, retropulsion (i.e. a tendency to fall backwards), rigidity, stooped posture, slowness of voluntary movements, and a masklike facial expression. Pathologic features include loss of melanin containing neurons in the substantia nigra and other pigmented nuclei of the brainstem. LEWY BODIES are present in the substantia nigra and locus coeruleus but may also be found in a related condition (LEWY BODY DISEASE, DIFFUSE) characterized by dementia in combination with varying degrees of parkinsonism. (Adams et al., Principles of Neurology, 6th ed, p1059, pp1067-75)Autistic Disorder: A disorder beginning in childhood. It is marked by the presence of markedly abnormal or impaired development in social interaction and communication and a markedly restricted repertoire of activity and interest. Manifestations of the disorder vary greatly depending on the developmental level and chronological age of the individual. (DSM-V)Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Obsessive-Compulsive Disorder: An anxiety disorder characterized by recurrent, persistent obsessions or compulsions. Obsessions are the intrusive ideas, thoughts, or images that are experienced as senseless or repugnant. Compulsions are repetitive and seemingly purposeful behavior which the individual generally recognizes as senseless and from which the individual does not derive pleasure although it may provide a release from tension.Azabicyclo Compounds: Bicyclic bridged compounds that contain a nitrogen which has three bonds. The nomenclature indicates the number of atoms in each path around the rings, such as [2.2.2] for three equal length paths. Some members are TROPANES and BETA LACTAMS.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Child Development Disorders, Pervasive: Severe distortions in the development of many basic psychological functions that are not normal for any stage in development. These distortions are manifested in sustained social impairment, speech abnormalities, and peculiar motor movements.Substance-Related Disorders: Disorders related to substance abuse.Phobic Disorders: Anxiety disorders in which the essential feature is persistent and irrational fear of a specific object, activity, or situation that the individual feels compelled to avoid. The individual recognizes the fear as excessive or unreasonable.Psychotic Disorders: Disorders in which there is a loss of ego boundaries or a gross impairment in reality testing with delusions or prominent hallucinations. (From DSM-IV, 1994)Automobile Driving: The effect of environmental or physiological factors on the driver and driving ability. Included are driving fatigue, and the effect of drugs, disease, and physical disabilities on driving.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Body Mass Index: An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)Work Schedule Tolerance: Physiological or psychological effects of periods of work which may be fixed or flexible such as flexitime, work shifts, and rotating shifts.Anxiety: Feeling or emotion of dread, apprehension, and impending disaster but not disabling as with ANXIETY DISORDERS.Sex Factors: Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.Neuropsychological Tests: Tests designed to assess neurological function associated with certain behaviors. They are used in diagnosing brain dysfunction or damage and central nervous system disorders or injury.Circadian Clocks: Biological mechanism that controls CIRCADIAN RHYTHM. Circadian clocks exist in the simplest form in cyanobacteria and as more complex systems in fungi, plants, and animals. In humans the system includes photoresponsive RETINAL GANGLION CELLS and the SUPRACHIASMATIC NUCLEUS that acts as the central oscillator.Receptor, Melatonin, MT2: A melatonin receptor subtype primarily found expressed in the BRAIN and RETINA.Delta Rhythm: Brain waves seen on EEG characterized by a high amplitude and a frequency of 4 Hz and below. They are considered the "deep sleep waves" observed during sleep in dreamless states, infancy, and in some brain disorders.Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Health Surveys: A systematic collection of factual data pertaining to health and disease in a human population within a given geographic area.Headache: The symptom of PAIN in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of HEADACHE DISORDERS.Sex Distribution: The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.Age Distribution: The frequency of different ages or age groups in a given population. The distribution may refer to either how many or what proportion of the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.Conduct Disorder: A repetitive and persistent pattern of behavior in which the basic rights of others or major age-appropriate societal norms or rules are violated. These behaviors include aggressive conduct that causes or threatens physical harm to other people or animals, nonaggressive conduct that causes property loss or damage, deceitfulness or theft, and serious violations of rules. The onset is before age 18. (From DSM-IV, 1994)Benzhydryl Compounds: Compounds which contain the methyl radical substituted with two benzene rings. Permitted are any substituents, but ring fusion to any of the benzene rings is not allowed.Positive-Pressure Respiration: A method of mechanical ventilation in which pressure is maintained to increase the volume of gas remaining in the lungs at the end of expiration, thus reducing the shunting of blood through the lungs and improving gas exchange.Benzodiazepines: A group of two-ring heterocyclic compounds consisting of a benzene ring fused to a diazepine ring.Stress, Psychological: Stress wherein emotional factors predominate.United StatesApnea: A transient absence of spontaneous respiration.Chronic Disease: Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care. (Dictionary of Health Services Management, 2d ed)Anti-Anxiety Agents: Agents that alleviate ANXIETY, tension, and ANXIETY DISORDERS, promote sedation, and have a calming effect without affecting clarity of consciousness or neurologic conditions. ADRENERGIC BETA-ANTAGONISTS are commonly used in the symptomatic treatment of anxiety but are not included here.Pulmonary Medicine: A subspecialty of internal medicine concerned with the study of the RESPIRATORY SYSTEM. It is especially concerned with diagnosis and treatment of diseases and defects of the lungs and bronchial tree.Longitudinal Studies: Studies in which variables relating to an individual or group of individuals are assessed over a period of time.Tic Disorders: Disorders characterized by recurrent TICS that may interfere with speech and other activities. Tics are sudden, rapid, nonrhythmic, stereotyped motor movements or vocalizations which may be exacerbated by stress and are generally attenuated during absorbing activities. Tic disorders are distinguished from conditions which feature other types of abnormal movements that may accompany another another condition. (From DSM-IV, 1994)Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Biological Clocks: The physiological mechanisms that govern the rhythmic occurrence of certain biochemical, physiological, and behavioral phenomena.Monitoring, Ambulatory: The use of electronic equipment to observe or record physiologic processes while the patient undergoes normal daily activities.Medical History Taking: Acquiring information from a patient on past medical conditions and treatments.HLA-DQ beta-Chains: Transmembrane proteins that form the beta subunits of the HLA-DQ antigens.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Intracellular Signaling Peptides and Proteins: Proteins and peptides that are involved in SIGNAL TRANSDUCTION within the cell. Included here are peptides and proteins that regulate the activity of TRANSCRIPTION FACTORS and cellular processes in response to signals from CELL SURFACE RECEPTORS. Intracellular signaling peptide and proteins may be part of an enzymatic signaling cascade or act through binding to and modifying the action of other signaling factors.Logistic Models: Statistical models which describe the relationship between a qualitative dependent variable (that is, one which can take only certain discrete values, such as the presence or absence of a disease) and an independent variable. A common application is in epidemiology for estimating an individual's risk (probability of a disease) as a function of a given risk factor.Tinnitus: A nonspecific symptom of hearing disorder characterized by the sensation of buzzing, ringing, clicking, pulsations, and other noises in the ear. Objective tinnitus refers to noises generated from within the ear or adjacent structures that can be heard by other individuals. The term subjective tinnitus is used when the sound is audible only to the affected individual. Tinnitus may occur as a manifestation of COCHLEAR DISEASES; VESTIBULOCOCHLEAR NERVE DISEASES; INTRACRANIAL HYPERTENSION; CRANIOCEREBRAL TRAUMA; and other conditions.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Statistics, Nonparametric: A class of statistical methods applicable to a large set of probability distributions used to test for correlation, location, independence, etc. In most nonparametric statistical tests, the original scores or observations are replaced by another variable containing less information. An important class of nonparametric tests employs the ordinal properties of the data. Another class of tests uses information about whether an observation is above or below some fixed value such as the median, and a third class is based on the frequency of the occurrence of runs in the data. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1284; Corsini, Concise Encyclopedia of Psychology, 1987, p764-5)Reference Values: The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.Suprachiasmatic Nucleus: An ovoid densely packed collection of small cells of the anterior hypothalamus lying close to the midline in a shallow impression of the OPTIC CHIASM.Receptors, Melatonin: A family of G-protein-coupled receptors that are specific for and mediate the effects of MELATONIN. Activation of melatonin receptors has been associated with decreased intracellular CYCLIC AMP and increased hydrolysis of PHOSPHOINOSITIDES.Borderline Personality Disorder: A personality disorder marked by a pattern of instability of interpersonal relationships, self-image, and affects, and marked impulsivity beginning by early adulthood and present in a variety of contexts. (DSM-IV)Somatoform Disorders: Disorders having the presence of physical symptoms that suggest a general medical condition but that are not fully explained by a another medical condition, by the direct effects of a substance, or by another mental disorder. The symptoms must cause clinically significant distress or impairment in social, occupational, or other areas of functioning. In contrast to FACTITIOUS DISORDERS and MALINGERING, the physical symptoms are not under voluntary control. (APA, DSM-V)Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Epilepsy: A disorder characterized by recurrent episodes of paroxysmal brain dysfunction due to a sudden, disorderly, and excessive neuronal discharge. Epilepsy classification systems are generally based upon: (1) clinical features of the seizure episodes (e.g., motor seizure), (2) etiology (e.g., post-traumatic), (3) anatomic site of seizure origin (e.g., frontal lobe seizure), (4) tendency to spread to other structures in the brain, and (5) temporal patterns (e.g., nocturnal epilepsy). (From Adams et al., Principles of Neurology, 6th ed, p313)Obesity: A status with BODY WEIGHT that is grossly above the acceptable or desirable weight, usually due to accumulation of excess FATS in the body. The standards may vary with age, sex, genetic or cultural background. In the BODY MASS INDEX, a BMI greater than 30.0 kg/m2 is considered obese, and a BMI greater than 40.0 kg/m2 is considered morbidly obese (MORBID OBESITY).BrazilPhotoperiod: The time period of daily exposure that an organism receives from daylight or artificial light. It is believed that photoperiodic responses may affect the control of energy balance and thermoregulation.Chi-Square Distribution: A distribution in which a variable is distributed like the sum of the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another.ItalyOdds Ratio: The ratio of two odds. The exposure-odds ratio for case control data is the ratio of the odds in favor of exposure among cases to the odds in favor of exposure among noncases. The disease-odds ratio for a cohort or cross section is the ratio of the odds in favor of disease among the exposed to the odds in favor of disease among the unexposed. The prevalence-odds ratio refers to an odds ratio derived cross-sectionally from studies of prevalent cases.Accidents, Traffic: Accidents on streets, roads, and highways involving drivers, passengers, pedestrians, or vehicles. Traffic accidents refer to AUTOMOBILES (passenger cars, buses, and trucks), BICYCLING, and MOTORCYCLES but not OFF-ROAD MOTOR VEHICLES; RAILROADS nor snowmobiles.Risk Assessment: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)Lymphoproliferative Disorders: Disorders characterized by proliferation of lymphoid tissue, general or unspecified.Movement Disorders: Syndromes which feature DYSKINESIAS as a cardinal manifestation of the disease process. Included in this category are degenerative, hereditary, post-infectious, medication-induced, post-inflammatory, and post-traumatic conditions.Brain Injuries: Acute and chronic (see also BRAIN INJURIES, CHRONIC) injuries to the brain, including the cerebral hemispheres, CEREBELLUM, and BRAIN STEM. Clinical manifestations depend on the nature of injury. Diffuse trauma to the brain is frequently associated with DIFFUSE AXONAL INJURY or COMA, POST-TRAUMATIC. Localized injuries may be associated with NEUROBEHAVIORAL MANIFESTATIONS; HEMIPARESIS, or other focal neurologic deficits.Health Status: The level of health of the individual, group, or population as subjectively assessed by the individual or by more objective measures.Motor Activity: The physical activity of a human or an animal as a behavioral phenomenon.Double-Blind Method: A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.Combat Disorders: Neurotic reactions to unusual, severe, or overwhelming military stress.Alcohol-Related Disorders: Disorders related to or resulting from abuse or mis-use of alcohol.Attention Deficit and Disruptive Behavior Disorders: Includes two similar disorders: oppositional defiant disorder and CONDUCT DISORDERS. Symptoms occurring in children with these disorders include: defiance of authority figures, angry outbursts, and other antisocial behaviors.Renal Dialysis: Therapy for the insufficient cleansing of the BLOOD by the kidneys based on dialysis and including hemodialysis, PERITONEAL DIALYSIS, and HEMODIAFILTRATION.Aging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.Regression Analysis: Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Speech Disorders: Acquired or developmental conditions marked by an impaired ability to comprehend or generate spoken forms of language.Predictive Value of Tests: In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.