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This is the Sleep Lexicon page. Here you will find the definitions to all sleep terminology. These words have been derived from academic research and may be used differently than in normal language. Whenever you see something new, take some time to think about it and see how it relates to other sleep concepts you understand. Enjoy!

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The Sleep Lexicon - Where you get sleep vocabulary

Adenosine - an organic compound that is a key mediator of sleep homeostasis. It inhibits arousal and causes sleepiness. Adenosine Triphosphate (ATP) is an organic compound and hydrotrope that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. As ATP energy is used the remaining molecule is Adenosine. Adenosine build up is a sleepiness modulator and as long as a person is awake it continues to accumulate. When the person take a nap or sleeps, Adenosine (and sleepiness) is dumped. 

Aging - growing old, mature. People at old age wake up more often during the night and earlier in the morning.

Autonomic nervous system - a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal.

Blind - unable to see because of injury, disease, or a congenital condition. The eyes, as with most parts of the body, serve two functions. One is for vision and the other is photo reception.  In the eye, there are retinal ganglion cells that are extremely sensitive to sunlight. These cells remain active in most blind people to communicate with the brain on time of day through sunlight.

Breathing exercises - exercises intended to promote effective and healthy breathing. Breathing exercises can open up the capillaries of the lungs, increase oxygen in the blood, cause a relaxation response, and assist with stretching. Breath control has demonstrated the ability to change heart rate, change brain function, and relax the autonomic nervous system. Breathing exercises can help with focus, relaxation, and sleep. Exist Tribe teaches several breathing techniques to include 4-sec breathing, box-breathing, 4/7/8 Breathing & VOO breathing.

Caffeine - a type of drug that promotes alertness. It blocks the adenosine receptors and reduces sleep pressure. Caffeine has a six hour half-life and can accumulate at high dosages. While caffeine blocks the receptors from adenosine, adenosine will continue to accumulate. When caffeine wears of, the adenosine can quickly attach to the receptors and cause overwhelming sleepiness. 

Calcium - a mineral that is necessary for life directly related to our cycles of sleep, combines with the tryptophan you've eaten to create melatonin.

Cerebrospinal Fluid (CSF) - a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. It replaces the body fluid found outside the cells of all bilateral animals. The CSF is produced by specialized ependymal cells in the choroid plexuses of the ventricles of the brain, and absorbed in the arachnoid granulations.

Cognitive Restructuring - a psychotherapeutic process of learning to identify and dispute irrational or maladaptive thoughts known as cognitive distortions.

  • NST (Negative Sleep Thoughts) - Coined by Dr. Greg Jacobs

  • PST (Positive sleep thoughts) - an optimistic attitude, the practice of focusing on the good in any given situation that helps the person have a good night sleep. Coined by Dr. Greg Jacobs

  • NAT (Negative Awake Thoughts) - Coined by Dr. Greg Jacobs

  • PAT (Positive Awake Thoughts) - Coined by Dr. Greg Jacobs

Cortisol - a steroid hormone produced by the HPA axis, which also helps coordinate your sleep cycles. 

Circadian cycle - a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. “Circa” meaning revolving, Dia - meaning “Day” So circadian rhythm meaning daily rhythm.

Deep Sleep - Slow Wave Sleep or NREM sleep also known as quiescent sleep, is, collectively, sleep stages 1–3, previously known as stages 1–4. 

Disturbances - Sleep Disturbances caused by wake-ups, get-ups and restless time during your sleep can have a big impact on your sleep quality and daytime cognitive performance. Restless sleep is less restorative than uninterrupted sleep, and it's usually the cause of daytime sleepiness. Disturbances can be caused by various different factors, such as stress, noise, partners, pets or different foods.

Dopamine - a type of neurotransmitter that plays a role in how we feel pleasure.


EMDR (Eye Movement Desensitization and Reprocessing) - a psychotherapy treatment that was originally designed to alleviate the distress associated with traumatic memories (Shapiro, 1989a, 1989b). After successful treatment with EMDR therapy, affective distress is relieved, negative beliefs are reformulated, and physiological arousal is reduced.


Frequent urination - needing to go more than eight times a day or waking up in the night to go to the bathroom more than once in the night.


K-complexes - short negative high voltage peaks, followed by a slower positive complex, and then a final negative peak, with each complex lasting 1-2 minutes.

Negative sleep thoughts - cognitions about the self, others, or the world in general that are characterized by negative perceptions and expectations that affect sleep quality.

Melatonin - a hormone made by the pineal gland, helps control the body's sleep cycle, and is an antioxidant, promotes consistent, quality rest.

NREM Sleep (Non-Rapid Eye Movement Sleep) - Deep Sleep or Slow Wave sleep also known as quiescent sleep, is, collectively, sleep stages 1–3, previously known as stages 1–4. 

Pregnancy insomnia - having difficulty falling asleep, staying asleep, or both. Women can experience insomnia during all stages of pregnancy, but it tends to be more common in the first and third trimesters.

REM Rebound - is the lengthening and increasing frequency and depth of rapid eye movement sleep which occurs after periods of sleep deprivation.

REM Sleep (Rapid Eye Movement) - sleep is a unique phase of sleep accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream vividly.

Slow Wave Sleep (SWS) - Deep Sleep or NREM Sleep also known as quiescent sleep, is, collectively, sleep stages 1–3, previously known as stages 1–4. 

Negative sleep thoughts - cognitions about the self, others, or the world in general that are characterized by negative perceptions and expectations that affect sleep quality.

Noise pollution - unwanted or excessive sound that can have deleterious effects on human health, wildlife, and environmental quality. As demonstrated by Alan Muzet, noise with peaks greater than 55 decibels can interrupt sleep cycles.

Magnesium - an abundant mineral in the body that helps the body relax, reduces stress and helps you sleep longer.

Meditation - a set of techniques that are intended to encourage a heightened state of consciousness while relaxing in a comfortable position.

Parasympathetic Nervous System - division of the autonomic nervous system, dominates during sleep, a good night's sleep contains plenty of parasympathetic domination that balances your daily stress responses.

Posture shifts - involving movement of half or more of the body, average 12 per night.


Relaxation response - our physical way of reversing the effects of stress and the physical stress response, occurs when the body is no longer in perceived danger. Techniques to achieve this include breathing exercises, meditation, yoga, and gratitude journaling.

Rest Node (Restorative Essential Sleep Technology) - a revolutionary new sleep product that eliminates the need for sleep pills and helps you get on a positive sleep routine.


Sleep - a condition of the body and mind that occurs over several hours every night, in which the nervous system is relatively inactive, the eyes closed, the postural muscles relaxed, and consciousness practically suspended.

Sleep Efficiency - Sleep efficiency is a measurement of your sleep quality. It's the percentage of time you actually spend asleep after going to bed. It's common for Sleep Efficiency to slightly decrease with age. 

Sleeping pills - a tablet of a drug which helps to induce sleep, such as chloral hydrate or a barbiturate sedative.


  • Eszopiclone - sold under the brand name Lunesta® (manufactured by Sepracor). It is less effective than some other insomnia treatments, but has several unique advantages. Eszopiclone has a much smaller chance of causing user dependence than other sleep aids, and is less likely to be used recreationally. It also works well for long-term use. The most frequent side effects reported are loss of coordination and dizziness.

  • Zaleplon - mainly used to treat insomnia, and is manufactured by King Pharmaceuticals under the brand name Sonata®. Although zaleplon is not a benzodiazepine, it produces many of the same side effects: anterograde amnesia (inability to remember, especially during the period of the drug’s use), confusion, daytime drowsiness, agitation, and hallucinations. Zaleplon is a habit-forming drug.


  • Zolpidem - manufactured under several trade names; the most familiar being Sanofi-Aventis’ Ambien®. It is indicated for short-term insomnia treatment. Prescription Ambien is used as a “no-go” pill by the U.S. Air Force to facilitate sleep for pilots after a mission. Zolpidem is also used off-label to manage restless legs syndrome. If taken for an extended period, zolpidem has the potential to become addictive or at least to induce dependence. It produces many side effects, among them: hallucinations and/or delusions, anterograde amnesia, decreased motor coordination, and impaired judgement.


  • Zopiclone - a short-acting hypnotic drug first developed by Sepracor, and currently produced by Sanofi-Aventis. In the United States, it is sold under the analogue of eszopiclone (see above), and sold under multiple other brand names worldwide. The most commonly reported side effects are a bitter metallic taste, dry mouth, and headache.


Sleep Spindles - short bursts of brain activity in the region of 12-14 Hz, lasting maybe half a second each, also known as “sigma” waves. The thalamus is involved in processing sensory input. Sleep spindles appear to target this brain region and suppress information about external stimuli to reduce the chance of the sleeper waking up. After intense study, a sleeper experiences an increase in sleep spindles in the areas that were being used during learning. Sleep spindles are likely involved in memory processing and help commit learned information to long-term memory. Studies show an increase in fast sleep spindles when people are learning new motor tasks such as finger tapping, leading researchers to believe that fast sleep spindles may play a role in motor sequence learning.


Somatic Therapy - a form of body-centered therapy that looks at the connection of mind and body and uses both psychotherapy and physical therapies for holistic healing. In addition to talk therapy, somatic therapy practitioners use mind-body exercises and other physical techniques to help release the pent-up tension that is negatively affecting your physical and emotional wellbeing.


Stimulus control - a phenomenon in operant conditioning that occurs when an organism behaves in one way in the presence of a given stimulus and another way in its absence.


Stress response - a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival.

Suprachiasmatic nucleus (SCN) - each of a pair of small nuclei in the hypothalamus of the brain, above the optic chiasma, thought to be concerned with the regulation of physiological circadian rhythms. The SCN is considered the body clock as it regulates all circadian rhythms. The SCN is directly connected to the optic nerve and the retina for tracking the time of day through sunlight.

Sympathetic Nervous System - division of the autonomic nervous system, associated with REM sleep.

Stage 1 (NREM1 or N1) - the stage between wakefulness and sleep, sometimes referred to as hypnagogic sleep, in which your muscles are still quite active and your eyes roll around slowly, and may open and close from time to time. In more scientific terms, stage 1 is the period of transition from relatively unsynchronized beta and gamma brain waves (with a frequency of 12-30 Hz and 25-100 Hz), which is the normal range for the awake state, to more synchronized but slower alpha waves with a frequency of 8-13 Hz, and then to theta waves with a frequency of 4-7 Hz.


Stage 2 (NREM2 or N2) - the stage of sleep in which muscle activity is paralyzed. Brain waves during stage 2 are mainly in the theta wave range, but N2 sleep is characterized by two distinguishing characteristics: sleep spindles and K-complexes. Together, these two waves protect sleep and suppress response to outside stimuli, as well aid in sleep-based memory consolidation and information processing. Dreaming is more common during this stage than in the other non-REM sleep stages, and this is also the stage during which “parasomnias” such as night terrors, sleep-walking, sleep-talking and bedwetting occur. Information processing and memory consolidation also take place during this stage.


Stage 3 (NREM3 or N3) - known as deep or delta or slow-wave sleep (SWS), characterized by delta brain waves with a frequency of around 0.5-4 Hz. During this stage, you are less responsive to the outside environment, yet still aware of sounds and other stimuli. Neuronal activity, brain temperature, breathing rate, heart rate and blood pressure are all at their lowest levels during stage 3 sleep. Much of muscle recover occur during N3 sleep. The brain can reduce in size by as much as 60% as Cerebrospinal Fluid rushes in to rinse away amyloid build up (known to cause Alzheimer's) and new immune cells are introduced.

Total Sleep Time - Total sleep refers to the total amount of time you spend in light, REM and deep sleep. The amount of sleep needed varies from person to person. As a general rule, the younger you are, the more sleep you need. Most adults need 7-9 hours to perform well and stay healthy. Getting a good amount of sleep for your age will keep your Total Sleep time in balance

Yoga - the ancient practice of stretching while breathing. Yoga is thought to be a spiritual discipline based on an extremely subtle science, which focuses on bringing harmony between mind and body. 


Please feel free to reach out with questions or additions to the Sleep Lexicon list. 

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