Life Span changes in SleepAims

To know and understand research into life span changes in sleep

Key concepts

• A developmental approach • Sleep quality reduction– REM reduction • 90,60,25,20,10

– SWS 3 and 4 reduction • GH reduction

• Cultural differences • Circadian phase disorders – Chronotypes

Adults

• Redline (2004) meta analysis shows us that as we age:– Total sleep decreases– Time to get to sleep increases– Night time wakings increases– Feeling refreshed on waking increases– Feeling sleepy in the day increases– Daytime naps increase

Life span changes Age related variations

Life span changes in sleep

• REM sleep in premature children is about 80% of total sleep time. In newborns, REM sleep counts for 50/60% of total sleep, and falls to about 25% for children. This falls further to 20% for young adults, whereas older adults (60s-70s) REM is about 10%.

*Use owls and larks to show how age causes the changes to sleep patterns; these are age related circadian phase disorders/fluctuations)*REM changes linked to Brain development and memory consolidation

Interestingly reduction to SWS34• In humans and animals there is a reduction in sleep stages S3

SWS and S4 SWS. By 60 we sleep less than half we did at 20 in these stages. This is also true of those suffering from (early) senile dementia.

• Therefore it is possible that the loss of these stages rather than the loss of sleep overall is related to a reduction in the ability to store new memories.

• However there are still people in their 80’/90s that lack S3 and S4 but are still cognitively unimpaired.

• Also we must remember that McCrae et al. (2005) have uncovered evidence that elderly people actually sleep longer hours than they report, and that part of this is because they frequently experience micro sleeps (cat naps) during the day.

Older adults Adults Teenagers Children Infants

Older adults Adults Teenagers Children Infants Sleep Phase advances are common (similar to the genetic chronotype FASPS)

90 min cycle 5 cycles -Continuous sleep -REM increases in each cycle

Experience sleep Phase delay due to age related hormone changes - owls(DSPS)

Sleep walking (under-developed sleep control mechanisms)

60 min cycleQuiet=NRemActive=REM -Non –continuous sleep -6 months circadian rhythm est.

Wake up a lot Immediate deep sleep

Circadian shift phase disorder–owls

It takes 20 minutes before they enter deep sleep

Micro sleeps during the day; make up lost sleep at night

sleep walking in3% of adults

Cultural differences: between and within cultures

Sleep walking/terrors 20% of children

REM sleeps counts for 50/60% of total sleep time

REM sleep is 10% of total sleep time in 60/ 70 year olds

young adults sleep 20% of total sleep time in REM

There is a similar reduction in sleep duration in 11-16 years in all cultures

25% of total sleep time is in REM

Premature babies sleep 80% of total sleep time in REM – possibly due to brain dev.

Wet dreams are a feature

Pages 18-19

Problems with Self reporting data

Unreliable

Subjective

REM reduction

Infant sleep

• Newborns spend about 17 hours a day sleeping. – About 50% in REM sleep.– Sleep is interrupted every 3-4hours

• By 6 months babies sleep longer– Sleep periods extend to about 6hrs and tend to be

more associated with night time– May be influenced by parents

Toddlers

• By 12 months– Total sleep has declined to

about 13 hours (Sheldon 1996)

– REM sleep has decreased to 4-5 hours

• 2-3 years– Day time naps still

common

What does the graph tell us?Even within a culture there are great differences across ages

Page 19 ... Final paragraph: conclusion

We must avoid culturally biased conclusions!

We cannot generalise from culture to culture; or from age group to age group within a specific culture.

400,000

A point to note is that there is a

similar reduction in sleep duration in 11-16 years in all

cultures

• Adolescent sleep has been a very popular subject lately. People are questioning the fact that it may be true that their teenage sons and daughters may need more sleep than they did as a child, that they are not turning into lazy, sleepy young adults by choice.

• Sometime in late puberty, the body secretes the sleep-related hormone melatonin at a different time than it normally does. – This changes the circadian rhythms that guide a person's sleep-

wake cycle. For instance, if you told your teen to go to bed at 10 p.m., she may end up staring at the ceiling until 1 or 2 a.m. waiting to fall asleep. At about 7:30 p.m. a teen feels wide awake and fully alert, unlike an adult who is starting to "wind down" and feel sleepier as the evening progresses so that at 10 p.m. the adult is ready to go to bed. The teen-agers "wind down" time takes place much later. Owls – Phase delay.

Changes Are Taking Place • Studies show that the changes taking place in their

bodies requires more sleep and they may be physically challenged to getting up early in the morning.

• Their internal biological clock may slow down in adolescence. That can account for not their being sleepy until 2 a.m. To think that their child, who once awoke at the crack of dawn and was eager to watch cartoons even on Saturday mornings has now by choice, turned into a lazy, sleepy, young adult who wouldn't wake up in the morning if a bomb went off in the next room, is trying to undermine their authority in some way.

Other comments

• Adolescent brains are going through a critical phase of development.

• Sleep is crucial to ensure healthy development• Hansen (2005) suggests that school start times

should be adjusted to accommodate this. E.g. no tests before 10am!

Adolescents

• Crowley (2007) showed that adolescent sleep patterns vary with the school year.– Circadian rhythms are reset on Mondays which result in

symptoms of jet-lag (where the EP is desynchronised).• Carskadon (1998) found A grade 16-18yr olds slept

an average of an hour a day longer than other students.

• During adolescence the brain is going through a critical phase of development and cognitive development. Sleep is crucial in ensuring that these changes occur efficiently.

Wolfson & Carskadon (1998)Pagel (2007)

RWA: Future Recommendations – start college later in the morning to cater for teenagers

Other factors that may impact sleep patterns?

• Adolescents: The cause is usually the social changes such as

• Sleeping longer at weekends.• Staying up later.• Reduced parental influence.

• Several environmental factors are also responsible for changes in sleep……..

Other comments ...

• Poor sleep is associated with depression, poor memory and greater use of over-the-counter sleep remedies.

• Healthy adults much less likely to nap. • Ancoli-Israel (2008) suggests poor sleep in

elderly may be due to ill health and medication rather than aging itself.

Evaluation: Objective measurements • Research into lifespan changes in sleep has been

conducted in numerous sleep laboratories throughout the world, and the changes noted in the different stages of sleep involving both the quantity and the quality of sleep have been replicated and are reasonably well established. This is particularly true with respect to normal infant sleep because since the 1970s the US National Institute of Health has conducted exhaustive research into this topic in the hope of discovering the cause of Sudden Infant Death Syndrome (SIDS), often referred to as ‘cot death’ (Dement, 1999).

Reporting difficulties• There are questions as to the external validity of laboratory-based

research into sleep. • Borbely et al (1981) questioned adults aged 65-83 years of age on their

sleeping habits. They found that as many as 60% of them reported taking frequent daily naps. While the elderly do find that their sleep becomes more interrupted, they continue to need about the same amount of sleep as they did in early adulthood, hence the need for daytime naps.

• These naps may account for the reduced sleep times recorded at night and it remains unclear whether total sleeping time always decreases in elderly people. There has also been a lack of research into normal sleep among the middle-aged.

• Dement (1999) believes that this is because they are so busy trying to raise families, succeed at work and so on, that they find less time to volunteer for sleep laboratory research. Ironically, their busy lives suggest that they are precisely the group that should be researched since it is also the time when the greatest number of sleep problems occur.

Methodological problems

• A major problem with all sleep research involves the measurement of sleep. In order to measure the physiology of sleep in a laboratory, willing participants have to be connected to a number of electrodes. This must affect the quality and quantity of sleep that they experience. For this reason, it is often preferred if participants can spend more than one night in the sleep laboratory so that they may get more used to sleeping with the equipment and wires in place.

Under researched co-sleep

• There are numerous factors that affect the quality and quantity of sleep experienced. Work patterns, children, aches and pains, and medication can all affect sleep patterns. One factor that is under-researched is the effect of sleeping with a partner. For many people the majority of their sleeping lives are spent sharing a bed with a partner and yet the effects of co-sleep are under-researched.

• This area of research would have practical difficulties in a laboratory but co-sleep patterns may be both qualitatively and quantitatively different from sleeping alone.

Individual Differences

• Borbely (1986) warns against the use of generalisations about sleep patterns for different age groups. He reports that Wilse Webb from the University of Florida found marked differences between different participants in his sleep studies. Webb found consistent data from the same participant on different nights but not across participants, even when drawn from the same age range. This suggests that sleep patterns may be determined more by an individual person’s constitution rather than a cruder measure of age.

Operationalisation of sleep• One difficulty with sleep research is to agree when sleep occurs.

Sleep onset is gradual and entails a predictable sequence of events rather than a discrete event. Three phases of sleep can be identified: Phase 1 – characterised by calmness and immobility. Phase 2 – characterised by decreased muscle tone and electroencephalograph changes and phase 3 – characterised by an auditory threshold increase and perceived sleep onset (Tyron, 2004) Many researchers use EEG measures as the sole basis for defining sleep, but as Allan Rechtschaffen (1994) states: EEG’s are reductionist

• “Physiological measures derive their value as indicators of sleep from their correlations with the behavioural criteria, not from any intrinsic ontological or explanatory superiority. Any scientific definition of sleep that ignores the behaviours by which sleep is generally known unnecessarily violates common understanding and invites confusion”

Reductionist It is argued that restricting the definition of sleep to one measure (such as EEG) is akin to defining intelligence as what an IQ test measures. As long ago as 1963, Kleitman cited a dozen studies showing discrepancies between behavioural and EEG sleep criteria, and questioned EEG as the sole basis for defining sleep. Although some of these issues have been resolved through newer criteria, the debate continues, particularly with the use of new mobile sleep measure recording devices, such as the wrist Actigraph, which, although easier to use, have question marks concerning their validity.

Cultural differences (traditions)

• In Northern and Central Europe and North America, adults tend to adopt a so-called monophasic pattern of sleep (that is, they sleep for one long period during the night) and much of the research outlined would be applicable to these countries.

• However, in a significant number of countries (around the Mediterranean, Central and South America), adults take naps during the afternoon (Polyphasic). These siestas enable people to avoid working in the hottest part of the afternoon. Night-time sleep is thus delayed until later in the evening.

• Borbely (1986) reports that only 42% of Greeks adopt this polyphasic sleeping pattern and that the practice of taking a siesta is on the decrease.

• However, in China, the custom of an afternoon nap (called xiu-xi) is still widely observed.

16 mark Essay

• Discuss life span changes in sleep (16m)– Evaluation only. (Age related changes)

• Compare and contrast differences between age groups• REM changes with – brain dev• SWS34 changes – Age related decline – GH and immune syst.• Cultural differences: mono/polyphasic • Cultural differences: Teenagers • Objective measurements • Reporting difficulties • Individual differences • Under researched groups • Methodological problems • Reductionist

Describe and evaluate research and/or explanations into the nature of sleep, an ultradian rhythm (24m)

AO1 Ultradian length EEG, EOG, EMG’SREM/nREM SWSBrain activity in each stageStage and activitySleep deprivation studies

-Human sleep studies -Animal sleep studies

Changes over a life time (see Life span PP on uniservity)

What they teach us about sleep

AO2/3 (IDA) Genetics NT’s influence Brian areas – case studiesImportance of psychology as a science Objectivity (myths)

Artificiality -Reductionist

Approach to study is reductionist Universality – Evolutionary (ad hoc)Individual differences Case studies – bias Fatal familial insomnia - genesEthics with humans Ethics with Animals Comparison studies Cross cultural studies – mono/poly