Sleep: Periodic, natural, reversible loss of consciousness- as distinct from unconsciousness resulting
from a coma, general anesthesia, or hibernation
- Physiological: Heart rate slows down, breathing becomes more irregular, muscles relax, and
sensory systems close down (starting with vision, then hearing, etc.)
- Neurological: Electric voltage increases with more diffuse firings throughout the brain
- Psychological: Awareness of time slips away, control of thought and imagery decreases,
hypnagogic hallucinations may occur (strange occurrences that are experience just before
Circadian Rhythm: the biological clock; regular bodily rhythms that occur on a 24-hour cycle
REM sleep: otherwise known as, rapid eye movement sleep, a recurring sleep stage during which vivid
dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed, but other
body systems are active
Alpha waves: the relatively slow brain waves of a relaxed, awake state
Delta waves: the large, slow brain waves associated with deep sleep
Hallucinations: false sensory experiences such as seeing something in the absence of an external visual
Why do we sleep? We need the rest and recovery time to be more replenished and active during the
day. During sleep our levels of Serotonin and Norepinephrine drop and acetylcholine increases.
Some effects of sleep loss consist of; increase in hunger, stress hormone (cortisol) which creates fat, and
impaired concentration and productivity.
Sleep theories… Why do we sleep?
1) Sleep protects – back in the hunter gatherer days, in order to avoid dangers of the night they
would sleep through it
2) Sleep helps recuperate – it helps restore and repair brain tissue, sleeping gives resting neurons
time to repair themselves
3) Sleep is for making memories – restoring and rebuilding our fading memories of the day’s
4) Sleep feeds creative thinking – On occasion dreams have inspired many artistic, literary, and
even scientific achievements. A complete night’s sleep gives to our thinking and learning.
5) Sleep may play a role in the growth process – During deep sleep, the pituitary gland releases a
growth hormone and we release less and less of this hormone as we spend less time in deep
sleep (as we grow older)
Insomnia: recurring problems in falling or staying asleep Narcolepsy: a sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse
directly into REM sleep, often at inopportune times
Sleep apnea: a sleep disorder characterized by temporary cessations of breathing during sleep and
repeated momentary awakenings
Night terrors: a sleep disorder characterized by high arousal and an appearance of being terrified; unlike
nightmares, night terrors occur during stage 4 sleep, within two or three hours of falling asleep, and are
Dreams: a sequence of images, emotions, and thoughts passing through a sleeping person’s mind.
Dreams are notable for their hallucinatory imagery, discontinuities, and incongruities, and for the
dreamer’s delusional acceptance of the content and later difficulties remembering it.
Manifest content: accordi