Wakefulness: A state in which there is an enhanced potential for sensitivity and an efficient responsiveness to external stimuli.Sleep: A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility.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.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.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.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.Arousal: Cortical vigilance or readiness of tone, presumed to be in response to sensory stimulation via the reticular activating system.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.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)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.Neuropeptides: Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells.Pons: The front part of the hindbrain (RHOMBENCEPHALON) that lies between the MEDULLA and the midbrain (MESENCEPHALON) ventral to the cerebellum. It is composed of two parts, the dorsal and the ventral. The pons serves as a relay station for neural pathways between the CEREBELLUM to the CEREBRUM.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.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Reticular Formation: A region extending from the PONS & MEDULLA OBLONGATA through the MESENCEPHALON, characterized by a diversity of neurons of various sizes and shapes, arranged in different aggregations and enmeshed in a complicated fiber network.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.Pharyngeal Muscles: The muscles of the PHARYNX are voluntary muscles arranged in two layers. The external circular layer consists of three constrictors (superior, middle, and inferior). The internal longitudinal layer consists of the palatopharyngeus, the salpingopharyngeus, and the stylopharyngeus. During swallowing, the outer layer constricts the pharyngeal wall and the inner layer elevates pharynx and LARYNX.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.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.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)Pulmonary Ventilation: The total volume of gas inspired or expired per unit of time, usually measured in liters per minute.Respiratory Mechanics: The physical or mechanical action of the LUNGS; DIAPHRAGM; RIBS; and CHEST WALL during respiration. It includes airflow, lung volume, neural and reflex controls, mechanoreceptors, breathing patterns, etc.Respiration: The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (= OXYGEN CONSUMPTION) or cell respiration (= CELL RESPIRATION).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.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)Tegmentum Mesencephali: Portion of midbrain situated under the dorsal TECTUM MESENCEPHALI. The two ventrolateral cylindrical masses or peduncles are large nerve fiber bundles providing a tract of passage between the FOREBRAIN with the HINDBRAIN. Ventral MIDBRAIN also contains three colorful structures: the GRAY MATTER (PERIAQUEDUCTAL GRAY), the black substance (SUBSTANTIA NIGRA), and the RED NUCLEUS.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)Ventilators, Negative-Pressure: Body ventilators that assist ventilation by applying intermittent subatmospheric pressure around the thorax, abdomen, or airway and periodically expand the chest wall and inflate the lungs. They are relatively simple to operate and do not require tracheostomy. These devices include the tank ventilators ("iron lung"), Portalung, Pneumowrap, and chest cuirass ("tortoise shell").BenzoxazolesMicrodialysis: A technique for measuring extracellular concentrations of substances in tissues, usually in vivo, by means of a small probe equipped with a semipermeable membrane. Substances may also be introduced into the extracellular space through the membrane.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.Delta Sleep-Inducing Peptide: A nonapeptide that is found in neurons, peripheral organs, and plasma. This neuropeptide induces mainly delta sleep in mammals. In addition to sleep, the peptide has been observed to affect electrophysiological activity, neurotransmitter levels in the brain, circadian and locomotor patterns, hormonal levels, psychological performance, and the activity of neuropharmacological drugs including their withdrawal.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)Body Temperature: The measure of the level of heat of a human or animal.Hypercapnia: A clinical manifestation of abnormal increase in the amount of carbon dioxide in arterial blood.Persistent Vegetative State: Vegetative state refers to the neurocognitive status of individuals with severe brain damage, in whom physiologic functions (sleep-wake cycles, autonomic control, and breathing) persist, but awareness (including all cognitive function and emotion) is abolished.Air Pressure: The force per unit area that the air exerts on any surface in contact with it. Primarily used for articles pertaining to air pressure within a closed environment.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.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.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.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Prosencephalon: The anterior of the three primitive cerebral vesicles of the embryonic brain arising from the NEURAL TUBE. It subdivides to form DIENCEPHALON and TELENCEPHALON. (Stedmans Medical Dictionary, 27th ed)Hypothalamic Area, Lateral: Area in the hypothalamus bounded medially by the mammillothalamic tract and the anterior column of the FORNIX (BRAIN). The medial edge of the INTERNAL CAPSULE and the subthalamic region form its lateral boundary. It contains the lateral hypothalamic nucleus, tuberomammillary nucleus, lateral tuberal nuclei, and fibers of the MEDIAL FOREBRAIN BUNDLE.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.Unconsciousness: Loss of the ability to maintain awareness of self and environment combined with markedly reduced responsiveness to environmental stimuli. (From Adams et al., Principles of Neurology, 6th ed, pp344-5)Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Hypothalamus: Ventral part of the DIENCEPHALON extending from the region of the OPTIC CHIASM to the caudal border of the MAMMILLARY BODIES and forming the inferior and lateral walls of the THIRD VENTRICLE.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 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.Chemoreceptor Cells: Cells specialized to detect chemical substances and relay that information centrally in the nervous system. Chemoreceptor cells may monitor external stimuli, as in TASTE and OLFACTION, or internal stimuli, such as the concentrations of OXYGEN and CARBON DIOXIDE in the blood.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.Theta Rhythm: Brain waves characterized by a frequency of 4-7 Hz, usually observed in the temporal lobes when the individual is awake, but relaxed and sleepy.Cerebral Cortex: The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulchi. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.Microinjections: The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Dreams: A series of thoughts, images, or emotions occurring during sleep which are dissociated from the usual stream of consciousness of the waking state.Thalamus: Paired bodies containing mostly GRAY MATTER and forming part of the lateral wall of the THIRD VENTRICLE of the brain.Spinocerebellar Tracts: Fibers that arise from cell groups within the spinal cord and pass directly to the cerebellum. They include the anterior, posterior, and rostral spinocerebellar tracts, and the cuneocerebellar tract. (From Parent, Carpenter's Human Neuroanatomy, 9th ed, p607)Respiratory Physiological Phenomena: Physiological processes and properties of the RESPIRATORY SYSTEM as a whole or of any of its parts.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.Locus Coeruleus: Bluish-colored region in the superior angle of the FOURTH VENTRICLE floor, corresponding to melanin-like pigmented nerve cells which lie lateral to the PERIAQUEDUCTAL GRAY.Serotonergic Neurons: Neurons whose primary neurotransmitter is SEROTONIN.Homeostasis: The processes whereby the internal environment of an organism tends to remain balanced and stable.Pharynx: A funnel-shaped fibromuscular tube that conducts food to the ESOPHAGUS, and air to the LARYNX and LUNGS. It is located posterior to the NASAL CAVITY; ORAL CAVITY; and LARYNX, and extends from the SKULL BASE to the inferior border of the CRICOID CARTILAGE anteriorly and to the inferior border of the C6 vertebra posteriorly. It is divided into the NASOPHARYNX; OROPHARYNX; and HYPOPHARYNX (laryngopharynx).Brain Waves: Wave-like oscillations of electric potential between parts of the brain recorded by EEG.Temazepam: A benzodiazepine that acts as a GAMMA-AMINOBUTYRIC ACID modulator and anti-anxiety agent.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Consciousness: Sense of awareness of self and of the environment.Consciousness Disorders: Organic mental disorders in which there is impairment of the ability to maintain awareness of self and environment and to respond to environmental stimuli. Dysfunction of the cerebral hemispheres or brain stem RETICULAR FORMATION may result in this condition.Tidal Volume: The volume of air inspired or expired during each normal, quiet respiratory cycle. Common abbreviations are TV or V with subscript T.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Behavior, Animal: The observable response an animal makes to any situation.Hypothalamic Hormones: Peptide hormones produced by NEURONS of various regions in the HYPOTHALAMUS. They are released into the pituitary portal circulation to stimulate or inhibit PITUITARY GLAND functions. VASOPRESSIN and OXYTOCIN, though produced in the hypothalamus, are not included here for they are transported down the AXONS to the POSTERIOR LOBE OF PITUITARY before being released into the portal circulation.Actigraphy: The measurement and recording of MOTOR ACTIVITY to assess rest/activity cycles.Activity Cycles: Bouts of physical irritability or movement alternating with periods of quiescence. It includes biochemical activity and hormonal activity which may be cellular. These cycles are shorter than 24 hours and include sleep-wakefulness cycles and the periodic activation of the digestive system.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)Electrodes, Implanted: Surgically placed electric conductors through which ELECTRIC STIMULATION is delivered to or electrical activity is recorded from a specific point inside the body.Chloral Hydrate: A hypnotic and sedative used in the treatment of INSOMNIA.Hypnotics and Sedatives: Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety.Automobile Driver Examination: Government required written and driving test given to individuals prior to obtaining an operator's license.Pedunculopontine Tegmental Nucleus: Dense collection of cells in the caudal pontomesencephalic tegmentum known to play a role in the functional organization of the BASAL GANGLIA and in the modulation of the thalamocortical neuronal system.Substantia Innominata: Tissue in the BASAL FOREBRAIN inferior to the anterior perforated substance, and anterior to the GLOBUS PALLIDUS and ansa lenticularis. It contains the BASAL NUCLEUS OF MEYNERT.Reaction Time: The time from the onset of a stimulus until a response is observed.Diaphragm: The musculofibrous partition that separates the THORACIC CAVITY from the ABDOMINAL CAVITY. Contraction of the diaphragm increases the volume of the thoracic cavity aiding INHALATION.Respiratory Muscles: These include the muscles of the DIAPHRAGM and the INTERCOSTAL MUSCLES.GABA-A Receptor Agonists: Endogenous compounds and drugs that bind to and activate GABA-A RECEPTORS.Alpha Rhythm: Brain waves characterized by a relatively high voltage or amplitude and a frequency of 8-13 Hz. They constitute the majority of waves recorded by EEG registering the activity of the parietal and occipital lobes when the individual is awake, but relaxed with the eyes closed.Medulla Oblongata: The lower portion of the BRAIN STEM. It is inferior to the PONS and anterior to the CEREBELLUM. Medulla oblongata serves as a relay station between the brain and the spinal cord, and contains centers for regulating respiratory, vasomotor, cardiac, and reflex activities.Adrenergic Neurons: Neurons whose primary neurotransmitter is EPINEPHRINE.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.Motor Activity: The physical activity of a human or an animal as a behavioral phenomenon.Raphe Nuclei: Collections of small neurons centrally scattered among many fibers from the level of the TROCHLEAR NUCLEUS in the midbrain to the hypoglossal area in the MEDULLA OBLONGATA.Preoptic Area: Region of hypothalamus between the ANTERIOR COMMISSURE and OPTIC CHIASM.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.Airway Resistance: Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow.Psychomotor Performance: The coordination of a sensory or ideational (cognitive) process and a motor activity.Receptors, G-Protein-Coupled: The largest family of cell surface receptors involved in SIGNAL TRANSDUCTION. They share a common structure and signal through HETEROTRIMERIC G-PROTEINS.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/)Signal Processing, Computer-Assisted: Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.Hypoglossal Nerve: The 12th cranial nerve. The hypoglossal nerve originates in the hypoglossal nucleus of the medulla and supplies motor innervation to all of the muscles of the tongue except the palatoglossus (which is supplied by the vagus). This nerve also contains proprioceptive afferents from the tongue muscles.Evoked Potentials: Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported.Apnea: A transient absence of spontaneous respiration.