1. SLEEP
THEORIES

2. SLEEP DEPRIVATION GOING WITHOUT SLEEP
PARTIAL SLEEP DEPRIVATION – less sleep than normal
Effects – tiredness, lack of energy, lapses in attention
TOTAL SLEEP DEPRIVATION - No sleep at all
Effects – anxiety disorders, hallucinations, paranoia.
Prolonged sleep deprivation can lead to impaired functioning of the immune system (Coren)
KK 4A – PAGE 153

3. SLEEP DEPRIVATION TOTAL SLEEP DEPRIVATION
RESULTS IN:
PSYCHOLOGICAL
PHYSIOLOGICAL
Anxiety Disorders
Hand tremors
Depression
Drooping eyelids
Hypertension
Difficulty focusing the eyes
Sleep Disorders
Lack of energy and strength
Hallucinations (false perceptions)
Slurred speech
Delusions (false beliefs)
Increased sensitivity to pain
Paranoia
Heart rate and body temperature drops
Impaired functioning of immune system
KK 4A – PAGE
It is difficult to judge if a person has total sleep deprivation due to microsleeps
This is a very short period of drowsiness or sleeping that occurs when the person is apparently awake

4. THE PURPOSE OF SLEEP RESTORATION & SURVIVAL
There are many different theories about why we sleep.
These theories include:
RESTORATION
&
SURVIVAL
KK 2 – PAGE 160

5. THE PURPOSE OF SLEEP RESTORATION
RESTORATIVE THEORIES OF SLEEP
(Recovery theories/Restore & Recovery Theories)
These theories propose that sleep provides ‘time out’ to help us recover from depleting activities during waking time that use up the body’s physical and mental resources
NREM REM
SLEEP SLEEP
KK 2 – PAGE

6. THE PURPOSE OF SLEEP RESTORATION –NREM SLEEP
REM REBOUND
People in sleep laboratories were regularly woken when they began REM sleep.
Researchers found that when they were allowed to sleep again, they spent longer in REM sleep than they normally would.
KK 2 – PAGE

7. THE PURPOSE OF SLEEP SURVIVAL
SURVIVAL THEORIES OF SLEEP (Meddis)
(Adaptive Theories/Evolutionary Theories/Preservation & Protection Theories)
These theories propose that sleep evolved to enhance survival by protecting an organism through making it inactive during the part of the day when it is most risky and dangerous to move about (Meddis, 1977)
EVIDENCE:
Animals with few natural predators sleep for longer periods of time
Animals with many natural predators sleep for shorter periods of time
We sleep at night because we need light to see
KK 2 – PAGE

8. EVALUATION
Survival theories do not explain why sleep involves a loss of awareness, since the loss of consciousness during sleep may place the organism at greater risk.
Limited evidence for the survival theories – but they do provide insights.
Overall – sleep has multiple purposes – two of which are restoration & survival.