Lifespan changes in sleep

1 year, Rest activity patterns are stabilising with 6-8 hours sleep at night supplemented by daytime naps of 1-2 hours. The proportion of REM approaches the adult ratio of about 25%.

Between 1&2 years old. The adult sleep-waking cycle is established though there may still be short naps in the daytime. 

Oswald proposed a 1/3 of sleep is spent in REM. massive brain growth where synaptic connections between neurons are being made. Supported by Lesku who found brain mass to be positively correlated with REM sleep, not NREM.

Ohayon et al.

5 and 70 years.

Total sleep time decreases from 470 mins-to 370 at age 70

Percentage of stage 1 NREM increases from 5.8 to 6.8

stage 2 NREM. 47 to 55%

Decrease in stages 3&4 NREM from 24% to only about 9%

(less need for REM sleep as an adult, Brain growth becoming less and less important)

Teenagers, around 9-10 hours sleep a night. lie ins. 

weekend a time to catch up on time lost.

Older ages 50+ see more naps, more time spent in NREM sleep. loss of REM sleep

The steady reduction in deep NREM, significantly as early as the age of 30, implies that the need for these functions declines with age. Older people with Alzheimers disease show a particular dramatic loss of deep NREM. They also have major problems with learning and memory and other brain functions, supporing a link between deep NREM and normal cogntive processes. 

Borbley, warns against the use of generalisations, Webb found consistent findings from the same participant across different nights, however did not across age group. The approach is nomothetic rather than idiographic, and we should be careful when generalising.