Self-generated cycle lasting about a day. Applies to sleeping, drinking, eating, urinating, hormone secretion, susceptibility to drugs, etc.
Endogenous circannual rhythms
Self-generated cycle lasting about a year.
Circadian or circannual rhythm that is not being periodically reset by light or other stimuli.
Desynchronization of biological clock from traveling across time zones.
Produced by the pineal gland. Makes us sleepy.
Small unpaired endocrine gland just posterior to the thalamus which produces melatonin 2-3 hours before bedtime.
Part of the hypothalamus located just above the optic chiasm. Connected to the retina by a branch of the optic nerve. Constitutes the biological clock.
Cue that resets the biological clock. Exercise, noise, meals, and temperature are secondary to light.
Combination of electroencephalograph (EEG) and eye-movement records.
Alternating between states of sleep and moderate arousal. No awareness of surroundings, no response to speech, no speech, or any purposeful activity. Show automatic response to pain (heart rate, breathing, sweating).
Minimally conscious state
Occasional, brief periods of purposeful action and limited speech comprehension.
No sign of any brain activity and no response to any stimulus.
Characteristic of relaxation, frequency of 8-12 per second.
Stage 2. 12-14 Hz during a burst lasting at least half a second. Results from interactions between cells in the thalamus and cortex.
Stage 2. Sharp, high-amplitude wave. Can also be caused in other stages by sudden stimuli.
Slow wave sleep (SWS)
Stage 3 and 4. Slow, high-amplitude waves become more common (neuron activity highly synchronized). Wave lasts >0.5s in Stage 4.
Deep sleep in some ways and light sleep in others. Refers to REM sleep.
Irregular, low-voltage fast waves indicate increased neural activity, but postural muscles such as those supporting the head are more relaxed than in any other stage.
Heart rate, breathing, and blood pressure are more variable than S2-4.
Intermittent facial twitches and eye movements.
Structure that extends from the medulla into the forebrain. Damage decreases arousal.
Part of the reticular formation that contributes to arousal.
"dark blue space". Silent at most times but emits bursts of impulses at meaningful, emotionally arousing moments.
Orexin (or hypocretin)
NT released in the basal forebrain and other areas. Essential for staying awake.
Anterior and dorsal to the hypothalamus. Provides axons that extend throughout the thalamus and cerebral cortex. Releases excitatory acetylcholine.
Waves of neural activity first in the pons, then in the lateral geniculate nucleus of the thalamus, and lastly in the occipital cortex.
REM deprivation results in the emergence of PGO waves during S2-S4.
Impaired ability to breathe while sleeping.
Frequent periods of sleepiness during the day.
Sudden muscle weakness, often triggered by strong emotions.
Periodic limb movement disorder
Repeated involuntary movement of the legs and sometimes the arms during sleep.
REM behaviour disorder
Move vigorously during REM sleep, seemingly acting out their dreams.
Experiences of intense anxiety from which a person awakens screaming in terror.
Extended period of unconsciousness caused by a head trauma, stroke, or disease.
Increases arousal by blocking receptors for adenosine, which accumulates during wakefulness and causes drowsiness.
The brain attempts to make a story out of haphazard input from various parts of the brain initiated by the PGO waves.