Biological Rhythms and Sleep

Question 1

Circadian Rhythm + Example

Answer 1

Occur about once a day.

Eg. Going to sleep/waking up, fluctuation of body temp

Question 2

Infradian Rhythm + Example

Answer 2

Occur less than once a day.

Eg. Menstrual cycle

Question 3

Endogenous pacemakers

Answer 3

Internal factors that influence biological rhythms

Eg suprachiasmatic nucleus

Question 4

Exogenous zeitgabers

Answer 4

External/environmental factors that regulate timing of biological rhythms
Eg. Daylight or alarm clocks

Question 5

Endogenous pacemakers in sleep wake cycle

Answer 5

Suprachiasmatic nuclei

Question 6

How does the SCN work

Answer 6

SCN sends signal to PINEAL GLAND to increase or decrease production of MELATONIN.

Question 7

Zucker

Answer 7

Found that if SCN cells are destroyed then sleep is distrupted.
Suggests SCN plays causal role in maintaining sleep-wake cycle.

Question 8

Inouye and Kawamura

Answer 8

Kept SCN tissue from animals alive in an organ culture seperate from rest of the brain. Even with no light, the cell showed a circadian rhythm.
Suggests SCN had internal circadian rhythm.

Question 9

Ralph

Answer 9

Took SCN from mutant golden hamster with 20hr rhythm and put it in a normal hamster on 24hr cycle. Normal hamster showed shorter rhythm.
SCN plays a role in determining length of the rhythm.

Question 10

Siffre

Answer 10

Lived in a cave for 6 months away from exogenous zeitgabers so his biological clock was ‘free running’. Settled on a 25 hour cycle.
Suggests exog and endog interact.

Question 11

Skene

Answer 11

Found that totally blind people have disrupted sleep wake cycles that do not fit 24 hour cycle.
Suggests external zeitgabers maintain and control the cycle.

Question 12

Folkard

Answer 12

Found that 11/12 people could not sleep properly on 22hrs cycle even though they thought they were on 24hrs.
Suggests endog pace control our sleep wake cycle.

Question 13

How does light influence the sleep/wake cycle?

Answer 13

Low levels of light»detected by photoreceptors in retina»suprachiasmatic nuclei»pineal gland»melatonin released»reduced brain activity»sleepiness

Question 14

DeCoursey

Answer 14

Deactivated SCN in 30 chipmunks and after 80 days significantly more of these chipmunks had been killed.
Suggests that they were more likely to be awake and moving in burrows.

Question 15

Practical implications of Ez and Ep research

Answer 15

Introducing melatonin tablets to increase levels of meletonin and make you feel sleepier.

Question 16

Nature/Nurture argument

Answer 16

Ep - Nature
Ez - Nurture
Interact with one another

Question 17

Dement and Klietmen

Answer 17

Studied 9 people for 61 nights in a sleep lab using EEG. Found there were different patterns of Rem and non Rem sleep

Question 18

Light sleep

Answer 18

Theta waves, slightly slower than when awake
Stage 1- may get sensation of eyes rolling back
Stage 2 -sleep spindles (bursts of activity)

Question 19

Slow Wave Sleep (SWS)

Answer 19

Delta waves (large, slow wave)
Stage 3
Stage 4 - deepest sleep, growth hormone secreted

Question 20

REM sleep

Answer 20

Aka Paradoxical sleep
Rapid Eye Movement
Brain waves similar to waking pattern, body paralysed, dreaming occurs

Question 21

Russell et al

Answer 21

Found women’s cycles synced when one woman’s sweaty wipes were rubbed under the others nose.
Suggests that pheromones are an influencing factor

Question 22

McClintock

Answer 22

Longitudinal - 135 students aged 17-22

Found that cycles synced for women who spent extended time together

Question 23

Menstrual cycle

Answer 23

Oestrogen levels rise causing uterus lining to thicken» Ovulation occurs, an egg is released by an ovary&raquo_space; if the egg is fertilised it attaches to uterus and develops

Question 24

Ultradian Rhythm + Example

Answer 24

Occur more than once in 24 hours.

Eg. Eating, stages of sleep

Question 25

Behavioural consequences of disrupting biological rhythms

Answer 25

Memory and concentration problems Lower productivity Chernobyl disaster occurred between 2-4

Question 26

Emotional/social consequences of disrupting rhythms

Answer 26

``` Anxiety, irritability, depression Relationship problems (particularly in shift work) ```

Question 27

Physical consequences of disrupting rhythms

Answer 27

Sleep problems inc difficulties falling or staying asleep Appetite problems Increased risk of heart disease and cancer Fatigue: Shift workers get 1-4 hrs less sleep per night

Question 28

Phase delay

Answer 28

Travel East to West....

Question 29

Backward rotation of shift

Answer 29

Nights >> Afternoons >> Morning

Question 30

Forward rotating shifts

Answer 30

Mornings >> Afternoons >> Nights

Question 31

Czeisler

Answer 31

Utah chemical plant operating in backward rotations changing every 7 days. Changed to forward rotating shift changing every 21 days. Workforce reassessed after 9 months: Stress levels- decreased Sleeping problems - decreased Productivity - increased

Question 32

Rafnsson

Answer 32

1,500 flight attendants | Found those who had been for over 5 years had over double the risk of breast cancer

Question 33

Kojo

Answer 33

Found no increase in the risk of breast cancer among fight attendants that couldn't be attributed to other risk factors (eg family history)

Question 34

Filipski

Answer 34

Recreated effect of chronic jet lag in mice by repeatedly phase advancing light dark cycle every 2 days. Found desynchronised mice experienced accelerated tumour growth

Question 35

Schernhammer

Answer 35

Used data of over 78000 US nurses and found significant correlation between number of years working shift and risk of breast cancer (even with other factors controlled for)

Question 36

Practical implications for research into distruption of sleep

Answer 36

Research on sleep and the impact of shift work should inform the legal decisions made about working patterns.

Question 37

Armstrong

Answer 37

Surveyed 3000 Australian parents and found their babies don't have a regular sleep pattern until 4 month 89% 3 month old babies have daytime naps

Question 38

Van Cauter

Answer 38

Studied 149 males (16-83) and followed for 14 years | Found that length of SWS decreased with age.

Question 39

Ohayon

Answer 39

Meta analysis of 65 studies found clear evidence of a decline in REM sleep from birth to old age

Question 40

Lifespan changes

Answer 40

Newborn babies sleep on average 17hrs a night, 50% of their sleep is REM 5 Year Olds - 25% SWS Adolescence often show phase delay where they wake up later and go to sleep later 70 Year Olds sleep 6hrs a night, 19% sleep is REM, 19% SWS

Question 41

Evolutionary theory - Energy conservation

Answer 41

1) Animals with high metabolic rates will sleep more than animals with low metabolic rate 2) Animals sleep more when food is scares 3) Newborns will sleep longer as they're smaller 4) Animals will sleep curled in warm places to maintain body temp

Question 42

Zeplin

Answer 42

Found negative correlation between animals body size and the amount of sleep they required across 53 species of mammals