PURPOSE OF SLEEP / RESTORATIVE SLEEP THEORY (+ / -) / EVOLUTION THEORY (+ / -) / OVERAL CRITICISMS

Question 1

DEFINITION: PURPOSE / FUNCTION OF SLEEP

Answer 1

• There may be more than one reason as to WHY we sleep
• Psychologists have identified a number of theories as to why we sleep. This includes:
  = Theory of RESTORATION
  = Theory of EVOLUTION / SURVIVAL

Question 2

DEFINITION: RESTORATION SLEEP THEORY

Answer 2

• Sleep provides us with a period of time to help us RESTORE our resources that have been DEPLETED during waking hours
• Physical resources = repairing and detoxifying muscles and eliminating waste products (Resources)

Question 3

RESTORATION SLEEP THEORY

• NREM sleep
• REM sleep

Answer 3

NREM: Restores, Repairs and Revitalises (RRR) the BODY

REM: Restpres, Repairs and Revitalises (RRR) the MIND

Question 4

RESTORATION SLEEP THEORY

* OVERVIEW 
= RR
= G
= M
= I to D
= A
= C M

Answer 4

• Repairs and Replenishes the body (RR)
• Sleep activates GROWTH hormones
• Sleep enhances MOOD
• Increases IMMUNITY to disease
• Increases alertness
• Consolidates memories

Question 5

RESTORATION SLEEP THEORY

• LIMITATIONS

Answer 5

• Has not conclusively established exactly WHAT is restored, repaired and revitalized during sleep
• Has not conclusively established exactly WHY it is not restored at OTHER times
• NOT been established that restoration is the only FUNCTION of sleep

Question 6

DEFINITION: EVOLUTION / SURVIVAL THEORY

Adaptive theory as well

Answer 6

• Also known as SURVIVAL, preservation and protection theories
• Sleep evolved to enhance SURVIVAL
• Protecting an organism through making it inactive during the part of the day when it is most RISKY or dangerous to move around
• RISKY / DANGEROUS = when predators are around
• While sleeping: Hiding = Less likely to attract their attention

Question 7

EVOLUTION / SURVIVAL THEORY

• OVERVIEW
• Animals that need more time to access food sleep LESS
• Large animal is vulnerable = need to be awake
• Mice = sleep more than larger animals (e.g. a deer)

Answer 7

• Sleep depends on the need to find FOOD
• Depends on vulnerability to predators (More time spent hiding and sleeping from predators)
• Humans = sleep at night to protect themselves
• Sleep CONSERVES energy
• Metabolism slowing = less need for FOOD

Question 8

EVOLUTION / SURVIVAL THEORY

• LIMITATIONS

Answer 8

• Does not explain WHY sleep involves a loss of awareness
• Loss of consciousness during sleep may place the organism at GREATER RISK
• Organism’s sense are LESS ATTUNED to the environment and predators
• Body is RELAXED and not ready to instantly respond to danger

Question 9

CRITICISMS OF THEORIES OF SLEEP

Answer 9

• Only LIMITED support for each theory
• No definitive answers to the question: Why we need sleep?
• Sleep seems to have multiple purposes, two of which are restoration AND survival