Biopsych - Biological rhythms

Question 1

Circadian rhythms

Answer 1

Last approximately 24 hours

Question 2

Endogenous pacemakers

Answer 2

Internal mechanisms that govern rhythms

Question 3

Exogenous zeitgebers

Answer 3

External factors (env, social) that reset biological clocks

Question 4

Impact of circadian rhythm: Boivin et al 1996

Answer 4

Shift workers have a period reduced concentration at 6am (circadian trough) = more mistakes

Question 5

Impact of circadian rhythm: Knutsson 2003

Answer 5

Shift workers are 3x more likely to develop heart disease than typical work patterns

Question 6

Impact of circadian rhythm: Charlene Solomon 1993

Answer 6

High divorce rates in shift workers is due to strain of deprived sleep (correlational methods, lack of causation)

Question 7

Impact of circadian rhythm: Bonten et al 2015

Answer 7

Co-ordinate basic functions -> heart rate -> chronotherapeutics or aspirin should then be taken last thing at night to prevent a heart attack early in the morning

Question 8

Teenagers sleep/wake cycle: Wolfson and Carskadon 1998

Answer 8

School day should start a couple hours later as melatonin secretion ends at 9am

Question 9

Teenagers sleep/wake cycle: Adolescent Sleep Working Group 2014

Answer 9

Benefits academic/behavioural performance when lessons begin later & reduced dependency on caffeine

Question 10

Teenagers sleep/wake cycle (other)

Answer 10

• Shifting the day is disruptive for parents & teachers
• Later school day would not reduce sleep deprivation since they would stay up later

Question 11

Individual differences in sleep/wake cycle: Czeisler 1999

Answer 11

Cycles can vary from 13 to 65 hours

Question 12

Sleep/wake cycle endogenous pacemakers

Answer 12

• Light received by Basal Ganglion cells
• SCN above optic chiasm passes on day length information
• Pineal gland secretes/inhibits melatonin
• Melatonin induces sleepiness

Question 13

Sleep/wake cycle exogenous zeitgebers

Answer 13

• Light -> research support (Campbell & Murphy - skin receptors on knees) vs critics (Folkard et al - time manipulation)
• Social cues -> research support (Baby research & entraining) vs critics (Laughton Miles blind man case)

Question 14

Infradian rhythms

Answer 14

Longer than 24 hour cycle

Question 15

Infradian rhythm: SAD

Answer 15

Exogenous system
Lack of light -> increases melatonin which reduces serotonin -> depressive symptoms

Question 16

Light therapy: SAD

Answer 16

Light boxes that produce 10K lux that are to be sat in front of for at least 30 mins in a morning to encourage melatonin reduction (most effective treatment but has side effects and 19% higher relapse rates [Rohan])

Question 17

Infradian rhythm: Menstrual cycle

Answer 17

Mainly endogenous system
Menstruation -> follicular phase -> ovulation -> luteal phase (24-35 day cycle, typically 28)

Question 18

EZs impacting menstrual cycle

Answer 18

• Pheromones (Stern & McClintock cotton pad, 68% sync)
• Light (Reinberg cave woman)
• Stress (increase/delay menstruation)

Question 19

Ultradian rhythms

Answer 19

Less than 24 hours

Question 20

Ultradian rhythms: sleep cycle

Answer 20

5 stages
1 - Light sleep, theta waves, high freq short amp
2 - Sleep spindles, consolidation of memories
3/4 - Slow wave sleep (delta), growth hormones & recovery, low freq high amp
5 - REM, dream sleep

Question 21

Support on stages in sleep cycle

Answer 21

• EEGs showing cyclic pattern of activation (Dermot & Kleitman - 33 participants)
• Ultramarathon runners have higher SWS -> used for recovery (Shapiro)
• EEGs showing increases REM for mental recovery post-overdose (Haider - 10 patients)