Sleep/Wake Cycle Flashcards
(25 cards)
What kind of rhythm is the sleep/wake cycle?
Circadian
What are endogenous pacemakers?
Internal body clocks that keep biological processes to time
What are exogenous zeitgebers?
External cues that entrain internal body clocks, meaning altering body clocks to match the environment
How long does a circadian rhythm last?
Around 24 hours
What do we have circadian rhythms for?
• Sleep/wake cycle
• Release of hormones
• Body temp
• Blood pressure
What is the SCN? (Suprachiasmatic Nucleus)
• The endogenous pacemaker for the sleep wake cycle known as the master clock
• Part of the hypothalamus in the limbic system
• Located at the optic chiasm, the point at which optic nerves cross
What happens when light is detected by the SCN?
Sends information to the pineal gland, stopping the production of melatonin, a hormone that results in a sleep response
What is the primary exogenous zeitgeber? And other examples of EZ?
Primary: Light
Other: Social cues, meal times, exercise, others going to bed, clocks
What was the Siffre study?
He stayed in a cave
What was Siffre testing?
If the circadian sleep/wake cycle endogenous pacemaker is be free running- maintaining a predictable cycle without constant entrainment by exogenous zeitgebers
How did Siffre test the theory of circadian rhythms?
• Spent 179 days (6 months) in a cave with no natural light, no clocks and isolated (no social cues)
What did Siffre find?
His body clock maintained a regular cycle of around 25 hours without EZ’s - slightly longer than the expected 24 hour cycle
What does Siffre’s test suggest?
The EP for the sleep/wake cycle is free running but needs entrainment to keep to the 24-hour day/night cycle
What is a critism of the use of natural lighting in isolated studies such as Siffre?
Psychologists suggest that the artificial lights disrupted measurements of the free-running circadian rhythm by acting as an EZ
- Czeisler found the circadian rhythm was closer to 24 hrs when artificial light was controlled
How does Vetter show evidence that light is an EZ?
When 27 office workers in an experimental group were exposed to strong blue light, they would shift their circadian rhythms to match the office lighting
A control group of 27 office workers with normal office lighting rhythm’s matched the shifting time of the natural light of dawn
What does Vetter’s study on office workers suggest?
• Light is an EZ
• Artificial lights can disrupt the EP by over-riding natural light as the primary EZ
What did Ralph’s study provide evidence for?
SCN is an EP
What was Ralph’s study on?
Golden hampsters (normal and ones with tau mutation)
What was Ralph’s procedure?
• Golden hampsters with Tau mutation have a circadian rhythm of 20 hours, compared to normal hampsters who have 24 hrs
• SCN from normal hampsters was transplanted into the brains of Tau mutant hampsters, the Tau hampsters gained a 24 hour sleep/wake cycle
• SCN from Tau hampsters transplanted into normal hampsters and they gained a 20 hour sleep/wake cycle
What does Ralph’s study suggest?
SCN is the main EP in the sleep/wake cycle
How will a psychological understanding of sleep pattern disruption lead to solutions to the negative effects of jet lag and shift work be a strength?
• Due to sleep pattern disruption lead to anxiety and decreased alertness/vigilance
• Would result in psychology having a positive effect on the wider economy
• Understanding the circadian blood pressure rhythm could help with drug taking timings and health treatments
How has knowing the psychological effects of exposure to light had implications in technology?
We are exposed to more blue light late at night from personal devices and new LED road lighting
- This provides people advice on how to maintain a healthy sleep pattern
Support that Light is the main EZ?
Research on a man blind from birth showed that even with social cues, the man had around a 25 hr circadian rhythm
- His sleep out of synchronisation with the rest of society
