acetycholine - a neurotransmitter involved in REM sleep




Advanced Sleep Phase Syndrome - This is a condition in which a patient wakes up too early in the morning and gets sleepy early in the evening. It is common in older people.




alpha waves - brain waves with a frequency of 8-13 cycles per second that are produced when a person is relaxed but awake.




antidepressant - a type of medication used to treat depression and related conditions. It tends to cause either insomnia or sleepiness it patients




Amphetamine - A colorless, volatile liquid, C9H13N, used primarily as a central nervous system stimulant.




apnea - a gap or pause in breathing




apnea index - the number of apneas per hour of sleep




atonia - lack of normal muscular tension or tonus




benzodiazepines - drugs that are used to relieve anxiety and to relax muscles, tending to cause sleepiness




beta waves - brain waves with a frequency of greater than 12 cycles per second that are produced when a person is awake and alert.




brain waves - electrical signals sent in the brain. They can be detected by electrodes placed on the scalp.




bright-light therapy - the use of bright lights for certain periods of time at a certain time of day to reset one's biological clock.




Bruxism - teeth grinding during sleep




cataplexy - a muscle weakness or paralysis. It is a symptom of Narcolepsy. It is often triggered by strong emotion.




Central Sleep Apnea (CSA) - a type of sleep apnea in which the brain briefly stops sending messages to the muscles to continue breathing, causing a pause in breath during sleep.




chronobiology - the study of the timing of biological systems




circannual rhythm - an internal biological clock that runs on a yearly cycle.




circadian rhythm - an internal biological clock that runs approximately on a 24 hour cycle.




Continuous Positive Airway Pressure (CPAP) - A mask worn by patients with sleep apnea that blows air from a tube to keep the airway open when the patient is sleeping.




crepuscular - twilight active. Some animals that are crepuscular are rodents, fish, and certain birds.




cytokines - compounds from the immune system, some of which are involved with the level of sleepiness. (pp. 103)




deep sleep - stages 3 and 4 of NREM sleep during which delta waves are produced.




Delayed Sleep Phase Syndrome - This is a condition in which a patient doesn't get sleepy until early in the morning the next day and sleeps late into the morning. It is common in older teens.




delta sleep - slow wave sleep, stages 3 and 4 of NREM sleep.




Delta Sleep-Inducing Peptide (DSIP) - a small protein that causes deed sleep when injected into animals




delta waves - brain waves with a high amplitude and a frequency of less than 4 cycles per second that are produced during deep sleep




diurnal - active during the day, asleep during the night




dormancy - a state of non activity during which sleep brain waves cannot be detected.




electroencephalogram (EEG) - a measurement of brain wave activity. This data is collected through sensors on the scalp.




electromyogram (EMG) - A measurement of muscle tension. The data is collected through sensors.




electrooculogram (EOG) - a measurement of eye movement. This data is collected through sensors.




enuresis - bed wetting

Excessive Daytime Sleepiness (EDS) - the symptom of being overly sleepy




fibromyalgia - A disorder characterised by muscle pain, stiffness and easy fatigability. The cause is unknown and an estimated 3 million are affected in the USA.

free-runing - a condition in which a subject is cut off from zeitgebers, allowing it to adjust to an individualized cycle.




hibernation - the state in which some animals spend the winter, with extremely low temperatures and metabolic rates. During this state, the brain shows no activity.




hypernyctohemeral syndrome - a condition in which the patient's sleep - wake cycle is one of 25-27 hours. (p. 104 encycl.)




hypersomnia - sleeping too much or being too sleepy during the day.




hypnagogic hallucination - vivid dreamlike visions experienced by some patients of narcolepsy.




hypnic jerk - when feeling a falling sensation when going to sleep, one jerks to stop from falling.




hypothalamus - a small structure at the base of a human brain that serves as a biological clock, regulating the sleep-wake cycle.




insomnia - the inability to fall asleep, to maintain sleep, or to get back to sleep at night.




interleukin-1 - a chemical in the body involved in the immune system that may cause sleepiness. (p. 104 encycl.)




jet lag - experienced when the biological clock is not synchronized with its surroundings because of a change in time zones.




lucid dreaming - being aware during a dream that one is dreaming




Medulla Oblongata - The lowermost portion of the vertebrate brain, continuous with the spinal cord, responsible for the control of respiration, circulation, and certain other bodily functions.




Melatonin - a natural hormone of the pineal gland. It is only released during the night.




microsleeps - occurrences of sleep during wakefulness lasting a few seconds.




Multiple Sleep Latency Test (MSLT) - a standardized procedure used to measure daytime sleepiness. During the test, the patient is asked to stay awake for certain lengths of time and then to take short-duration naps when requested.




Muramyl Dipeptide (MDP) - a substance that raises body temperature, activates the immune system, and increases the amount of NREM sleep sleep when injected into animals




myuoclonus - unintentional twitching or tightening of a muscle




myoclonus index - the number of leg jerks per hour of sleep




narcolepsy - a sleep disorder in which the patient has an irresistible need to sleep during the day. A patient may also experience cataplexy sleep paralysis, hypnagogic hallucinations, and or sleep working.




Neural Gerbage Collection - a theory that dreaming is used to discharge unwanted information from one's memory




neuroscience - the scientific study of the nervous system.




neurons - cells that pass electrical signals to, from, and within the brain




neurotransmitters - chemicals that carry electrical signals between neurons




nightmares - frightening and vivid dreams that occur during REM sleep




night terrors - (pavor nocturnous) episodes in which a sleeper wakes up suddenly and screams. The person is panicked, frightened, and confused, and returns to sleep within half an hour. The patient has no memory of the event in the morning.




nocturnal - active at night time.




nocturnal myoclonus - periodic limb movements in sleep




Non - Rapid Eye Movement (NonREM, NREM) Sleep - A type of sleep that is divided into four stages. Usually about 75% of the night is spent in NREM Sleep.




norepinephrine - a neurotransmitter involved in the muscle paralysis during REM sleep




Obstructive Sleep Apnea (OSA) - A type of sleep apnea in which the muscles in the throat collapse, blocking the airway.




parasomnias - physical events that occur during sleep




Periodic Limb Movements in Sleep (PLMS) - a sleeping disorder in which the patient's arms or legs jerk during sleep, causing brief arousals




pharynx - part of the back of the throat. Its muscles' relaxation can cause snoring.




phisostigmine - a drug that acts like acetylcholine, inducing REM sleep (p. 105 encyc.)




Physiology - The biological study of the functions of living organisms and their parts.




pituitary gland - a control system for many hormones. It is located in the brain.




polysomnography (PSG) - the recording of different biological factors during sleep, such as brain waves, muscle tension, and eye movement.




pons - the part of the brain that controls REM and NREM sleep. (p. 105 encycl.)




prostaglandin D2 - a cytokine that enhances sleep




Psychology - The science that deals with mental processes and behavior.




psychotherapy - The treatment of mental and emotional disorders through the use of psychological techniques designed to encourage communication of conflicts and insight into problems, with the goal being personality growth and behavior modification.




quiet sleep - nonREM sleep.




Rapid Eye Movement (REM) Sleep - A type of sleep during which the body is paralyzed and the eyes move. Dreaming occurs during this sleep.




Rapid Eye Movement (REM) Sleep Behavior Disorder - a sleep disorder in which the person's body is not paralyzed during REM sleep and so the patient acts out his or her dream, which can have dangerous consequences.




Restless Legs Syndrome - A disorder in which the patient experiences and uncomfortable sensation in the legs eased only by moving them. These sensations occur when the patient is relaxed.




retina - the portion of the eye that receives light




Sentinel Hypothesis - the theory that the brain gathers external stimuli during REM sleep to look out for danger. Any sounds or other stimuli gathered are then incorperated into the dream.




serotonin - a neurotransmitter that affects how alert one is




shallow torpor - a state of inactivity and little breathing




Sleep Apnea - a sleep disorder in which the sleeper has many pauses in breathing during the night, causing a brief arousal.




sleep efficiency - the parcentage of time in bed that one is actually asleep.




Sleep Hygiene - good sleep habits, such as going to bed and waking up on time, eating and exercising appropriately, etc.




sleep latency - the amount of time it takes one to fall asleep.




sleep paralysis - the inability to move in sleep during REM sleep and when wakening from REM sleep. Narcoleptics often experience this when falling asleep.




sleeptalking - a parasomnia in which the sleeper talks or mumbles words or nonsense while sleeping and has no memory of it in the morning. This is a normal behavior.




sleepwalking - a parasomnia in which the sleeper gets out of bed during sleep and walks around, perhaps even performing routine tasks. The sleeper has no memory of the occurrence in the morning.




slow-wave sleep - stages 3 and 4 of NREM sleep, during which the brain waves are large and slow. These are usually the deeper stages of sleep.




snoring - a phenomena that occurs during sleep when the sleeper's airway is narrowed, disturbing the airflow.




somnambulism - sleepwalking




somniloquy - sleep-talking




Sudden Infant Death Syndrome - unexplained death of seemingly healthy babies




suprachiasmatic nucleus - the part of the hypothalamus that controls the sleep-wake cycle




theta rhythms - brain waves with a frequency of about 6 cycles per second. Humans do not produce theta rhythms (which are different from theta waves). Many animals, however, do produce these waves during REM sleep, times of crisis (such as being hunted) or when preforming an essencial task (such as hunting).




theta waves - brain waves with a frequency of 4-7 cycles per second that are produced during light sleep.




thyroid - a gland involved in the use of energy




thyrotropin - a hormone released by the pituitary gland involved in the stimulation of the thryroid gland




tracheostomy - surgury sometimes used to improve conditions of those with extremely severe cases of obstructive sleep apnea




type II interferon - a cytokine that induces sleep




Uvula - A small, conical, fleshy mass of tissue suspended from the center of the soft palate.




Uvulopalatopharyngoplasty (UVPPP) - operation sometimes used to treat patients with obstructive sleep apnea




woodchuck - a hibernating animal




zeitgebers - external cues that reset the biological clock to be synchronized with the outside world.