List
What are 5 things that you
absolutely must do on a daily
basis?
Consider this
The average teenager in America will spend 65 days
(1560 hours) watching T.V.
The average American will spend 60 hours on HOLD
The 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
Rhythm of Sleep
Illustration © Cynthia Turner 2003
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.
5
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
90-Minute Cycles During Sleep
With each 90-minute cycle, stage 4 sleep decreases
and the duration of REM sleep increases.
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Sleep Deprivation
Stages of Sleep & Time Spent in
Each Stage
Changes over Time to Sleep Type
and Amount
Stages of N-REM & REM
Accidents
Frequency of accidents increase with loss of sleep
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