- Infancy: Infants tend to sleep about 16 hours a day (it is not continuous), shorter sleep cycles then adults do so they last less than 90 minutes, they have immature versions of SWS and REM sleep however theres is known as quiet sleep and active sleep, at bith there is more active sleep than adult REM sleep, half of an infant’s sleep is spent in active sleep, infants during early months enter sleep through an initial period of light sleep (unlike adults who go directly into the state of deep sleep), enter deep sleep after about 20 minutes, after about 6 months their circadian rhythm has been established (sleep-wake cycyle), by age of one infants mainly asleep mainly at night-periods of deep sleep lengthen and there is a reduction in the amounts of active/REM sleep
- Childhood: by age offive children have EEG patterns that look like those of an adult but they still sleep more and having more REM activity (around 30% of total sleep time), boys sleep slightly more than girls, more common for children to experience a variety of parasomnias (sleep disorders) such as sleep walking or night terrors which are severe nightmares
- Adolescence: need for sleep increases to about 9/10 hours a night, circadian rhythms change so they naturally feel more awake later at night and have more difficulty getting up early (called a phase delay), one distinguised feature of adolescent REM sleep in males is that it is sometimes accompanied by orgasm/ejaculation (less likely at other ages)
- Adult/old age: ‘normal’ adult sleep is for around 8 hours a night with 25% in REM sleep , sleep walking is more rare, increase in other sleep disorders such as insomnia and apnoea, older people find it harder to get to sleep and wake up around 6 times per night=more likely to nap in the day, REM sleep decreases to about 20%, slow wave sleep is reduced to as little as 5% , NREM sleep increases, suffer from phase advance of circadian rhythms (feeling sleepier earlier in the evening and waking up earlier)
Ohayon et al (2004) carried out a meta analysis on lifespan changes in sleep. They found that;
- Total sleep requirement drops from 8-11 hours at age 5, to 6 hours at age 70.
- At age 70, people spend longer in sleep stages 1 and 2, then they do as a child.
- Durations of stage 3 and 4 sleep drop dramatically at age 70. (9% compared to 24% at age 5).
New born babies spend more time in REM sleep than 12 month olds, suggesting REM sleep may be vital for their brain growth and development - however, is not fully understood why REM sleep is so vital for this to occur.
- Van Cauter et al (2000)- carried out a longitudinal sleep study on 149 male pps aged 16-93 years old, over a 14 year period, found that deep sleep and production of growth hormone wasv reduced between 16-35 years old and 35-50 years old, showing that between these years the amount of repair to body tissues is reduced, by the age of 45 there is little growth and repait that muscle tone begins to commonly fade, exericse becomes more difficult, Van Cauter et al linked this finding to an evolutionary perspective as when we were hunter-gathers our life expectancy would have been significantly lower, therfore there was no need to carry on growth hormones and repairs=no deep sleep needed
Outline lifespan changes in sleep. [4 marks]
Describe and evaluate life span changes in sleep (9 and 16 marks)
- ^^ good example essay
Good essay plan:
Good youtube video, made by fellow student;