Differences in the Demands of Sleep Across the Lifespan

Question 1

Differences in the Demands of Sleep Across the Lifespan

Answer 1

● From birth onwards, the total amount of time spent asleep gradually decreases.
● The proportion of time spent in REM sleep decreases.
● There is an age-related decrease in the proportion of NREM sleep that persists through to a very old age.

Question 2

Birth - 2 Months

Answer 2

● Sleep onset occurs during REM (not Stage 1 NREM) & occurs at any time (day or night)
● Sleep rhythms and duration are irregular (sleep episodes vary from 30 mins to 3-4hours)
● Alternation between NREM & REM is present, but fewer sleep cycles (1 or 2)
● 50% of sleep is REM or active sleep (similar to REM, but there may be more
movement)
● REM may be involved in early brain development
● Circadian rhythms are not fully developed

Question 3

2 Months - 3 Months

Answer 3

● Circadian rhythms start to exert influence (particularly melatonin)
● NREM-REM sleep cycles become more regular
● Sleep onset occurs in Stage 1 NREM

Question 4

6 Months

Answer 4

● Longest sleep cycle extends to approx. 5-8 hours
● All 3 stages of NREM are present during sleep
● Muscle paralysis typical of REM has set in

Question 5

Twelve Months

Answer 5

● Sleeping 14-15 hours a day with a large single sleep episode at night
● Proportion of REM is still high compared with childhood & adolescence

Question 6

Two - Five Years

Answer 6

● Total sleep decreases (approx. 13 to 11 hours) for biological (EG: maturation) & social reasons (EG: attendance at preschool)
● Total REM continues to decrease
● Total NREM increases (50% of NREM is stages 3)
● Arousal threshold during stage 3 is very high
● Young children o en skip their 1st REM period.

Question 7

Adolescents

Answer 7

● Total sleep time decreases
● By mid adolescence:
○ First REM not skipped
○ Sleep cycles resemble a young adults
○ Reduced NREM 3, but more time in NREM 2
● Adolescents do not get the required amount of sleep to function effectively
○ Reasons being the biological ‘adolescent sleep-wake cycle shi ’ delays
sleep onset by 1-2 hours.

Question 8

Adults

Answer 8

● Average 8 hours sleep a night
● 20-25% of sleep episode in REM
● Reductions in REM & NREM (particularly Stage 3) as we age
● Eventually Stage 3 disappear (particularly in males)
● Sleep more fragmented (older people wake more regularly in the night)
● Advanced Sleep Phase Syndrome: older people tend to sleep earlier in the
evening and wake earlier too
○ May be due to deterioration of the SCN

Question 9

Late Adulthood

Answer 9

● 6-7 Hours of sleep
● Less deep sleep - maybe only 1 cycle at the start of the night
● Multiple awakenings