Stages of and lifespan changes in sleep

Question 0

Dement and Kleitman: 9:61 sleep lab

Answer 0

• Sleep consists of clearly differentiated stages of brain activity.
• 9 ppt up to 61 nights in lab, waking them during each stage.
• All ppts showed quite considerable similarity in their sleep cycles. -Found 80-90% of ppts reported dreams during REM wakening
• Whereas only 7% recalled dreams from NREM awakening.
• Findings stand tests of time; accepted by scientific community in providing ^ES for the 5 stages of sleep.

Question 1

Discuss the 5 stages of sleep? (ALPHA & THETA➡️DELTA➡️BETA)

Answer 1

• 5 stages of sleep each cycle lasting approximately 90 minutes.
• starts NREM sleep (1-4) progresses from shallow to deep sleep.
• Back through stages 3-2- a short period of REM sleep which get longer during the course of the night.
• Stage 1 and 2 of NREM brain produces alpha and theta waves causing vHR/ vBT, sleeper in relaxed state SO easily woken.
• stages 3 and 4 NREM delta waves initiate deep/slow wave sleep.
• physiological repair/biochem processes take place during SWS.
• REM brain produces beta waves resemble the awake brain.
• known as paradoxical sleep as brain, eyes and major organs are active but body paralysed. REM is associated with dreaming.

Question 2

Dement: low population validity

Answer 2

• lack of population validity, scarcity of middle aged volunteers.
• Dement acknowledges that this is due to them being busy with family and work life hence they find less time for sleep research.
• Ironically, their lifestyles put them most at risk of sleep disorders.
• Making them more valuable subjects for Sleep research.
• Sleep knowledge limited due to inadequate sampling; undermines the 5 stage explanation.

Question 3

Foulkes: contradiction (70% NREM)

Answer 3

• Regardless, some contradictory R reported figures as high as 70% for dreams during NREM sleep.
• Foulkes attributed this to confusion as to wha constitutes a dream. -Dreams are subjective thus confused with muddled thoughts.
• AT REM identified by objective measure of brain activity there is no objective measure to accurately record dreams all relies on self reports.

Question 4

Psychology as a science:

Answer 4

• ^internal validity due to scientific approach in a lab setting.
• offers support to the debate of psychology as a science.
• Evidence is provided for BM behind sleep.
• // to measure sleep physiologically willing ppt wired up to machines which must affect the quality and quantity of sleep.
• Although R = ^ IV it lacks EV as it doesn’t reflect range of factors which influence real-life sleep i.e co-sleeping.
• Exp are undermined by a lack of practical application.

Question 5

Lifespan changes
(B 16-20 50%➡C ️12 30%➡A ️10 hours➡A ️8 25%➡O ️20%)

Answer 5

• Babies; polyphasic sleep approx 16-20 hours a day.
• Sleep cycles are shorter (45-60)
• Babies spend 50% of sleep in REM; brain growth and learning
• Children: 12h adolescents: 10h both approximately 30% REM.
• C:Often experience parasomnia i.e sleep walking and night terrors.
• A:Experience phase delay CR, difficulty getting to sleep/up early.
• Adulthood: on average 8 hours sleep per night with 25% REM
• Elderly: total sleep consistent // wake up more often, 20% REM.
• Older people = phase advance of CR, tired earlier/waking earlier.

Question 6

Tynjala et al: Israeli 8.5, Swiss 9.5, KA 6.5

Answer 6

• Found SP may not be universal; CF may also play a role.
• Over 40,000 children; found on average Israeli slept least at 8.5hrs while Swiss children slept the most at 9.5hrs.
• Important element here appeared to be ROE (nurture) with children spending late evenings outside the home = slept late.
• // Korea average sleep = 6.5hrs for adolescents = differences in SP. -Sleep patterns not dictated completely by nature but env f also play role in different sleep patterns and length.

Question 7

Brobely: Cultural bias (Greek polyphasic)

Answer 7

• Targeted primarily at western culture; adopt a monophasic sleep pattern (one long period of sleep during the night).
• // in sig number countries (Mediterranean) adults nap during PM avoid working during hottest part of day.
• Brobely found only 42% of Greeks adopted a Polyphasic pattern (multiple short sleeps); practice is on the decrease.
• Two things: even within cultures there’s individual differences in sleep patterns
• Globalisation/24 hour lifestyles are influencing all cultures sleep patterns. sleep not only change with age but is culture and lifestyle dependant, two factors ^ unrepresented in such R.

Question 8

Evolution: premature babies

Answer 8

• Evolutionary para = reason babies SP so different from adults; two-fold adaptive mechanism.
• More sleep = more REM sleep; necessary for brain development/L
• Daytime sleeping allows parents to complete chores enhance surv
• FM study = premature babies spend 90% of time in REM sleep; develop under-developed brains.exp ^ REM sleep than adults.

Question 9

Van Cauter et al: v Q & Q of sleep

Answer 9

• Found some of symptoms of old age; low bone density tiredness explained via reduction of SWS and associated protein synthesis.
• v sleep in old age; problems staying asleep; sleep apnoea or MI
• R treatment implications; improve QOL for elderly; calcium tablets
• Demo both RLPA of research into LC in S + how important R is in influencing medical understanding.