ListWhat are 5 things that
you absolutely must do on a daily basis?
Consider thisThe average teenager in America will spend 65
days (1560 hours) watching T.V.The average American will spend 60 hours on
HOLDThe average Englishman will spend 6 (36hrs/year) minutes a day laughing
Why Do We Sleep The Repair Theory – suggest that activities during
the day deplete key factors in our brain or body that are replenished or repaired by sleep.
Support (Sleep is needed to grow & create meaningful memories, repair its immune system and restore energy and chemicals During Stage 4 sleep marked secretion of growth
hormone
Increased production of of immune cells to fight infection
Glycogen is depleted during wakefulness and restored during sleep
Continued Adaptive Theory – suggests that sleep evolved because it
prevented early humans and animals from wasting energy and exposing themselves to the dangers of nocturnal predators Maximize our safety and survival
Ex. Taking a midnight stroll
Support - primarily from observing other animals (prey and predators) Lions – often, whenever, wherever (15 hours a day)
Many birds “unihemispheric sleep” Mallard Ducks
Seals and whales
Bats sleep 20 hours
The 2 Theories are not mutually exclusive
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Rhythm of Sleep
Circadian Rhythms occur on a 24-hour cycle and include sleep and wakefulness,
which are disrupted during transcontinental flights.
Light triggers the suprachiasmatic nucleus to decrease(morning) melatonin from the pineal gland
and increase (evening) it at night fall.
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2 major categories of Sleep
REM Sleep – Rapid Eye Movement When in REM sleep the eyes dart back and
forth
Non-REM Sleep – is where you spend approximately 80% of your sleep. It is divided into 4 Stages
Electroencephalogram (EEG)
REM Sleep Characteristics
Body and brain are in a general state of physiological arousal (blood pressure and heart rate may be 2x as high) – “paradoxical sleep”
Brain waves are very similar to Beta waves (awake)
Lose muscle tension in neck and limbs – essentially paralyzed – evolutionary advantageous
Makes up about 20% of sleep – pass through about 5-6 x
Remain in REM stage between 15-45 minutes
This is when we primarily are dreaming (80-90%)
REM rebound – refers to individuals spending an increased percentage of time in REM sleep if they were deprived of REM sleep on the previous nights.
Important Findings – Nader & Stickgold 2003 –suggests a correlation between REM sleep and store and encode memory
4 Stages of Non-REM Alpha Stage – marked by feelings of being relaxed and drowsy, usually
with eyes closed
Stage 1 (Theta waves)
Transition from wakefulness to sleep lasting 1-7 minutes
Lose responsiveness to stimuli and experience drifting thoughts and images
Arousal report having been awake
Stage 2 (1st Stage of Real Sleep)
Muscle tension, heart rate, respiration & body temp. drop
Sleep spindles
Minor noises won’t disturb you
Stage 3 & 4 (slow wave or Delta sleep)
Deepest stage of sleep – difficult to be awakened
Marked secretion of growth hormone
Sleep walking and talking occur during this stage of sleep
Changes during the Night
REM and Non-REM continues to alternate throughout the night
Stages 3&4 become shorter and REM tends to get longer and closer together
Although these cycles exist they are also irregular between people or within a given individual
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90-Minute Cycles During Sleep
With each 90-minute cycle, stage 4 sleep decreases and the duration of REM sleep
increases.
Sleep Deprivation
Stages of Sleep & Time Spent in Each Stage
Changes over Time to Sleep Type and Amount
Stages of N-REM & REM
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Accidents
Frequency of accidents increase with loss of sleep