Circadian rhythms

Question 1

What is a biological rhythm?

Answer 1

Distinct patters of change in body activity thst conform to cyclical time periods → are influenced by internal body clock EPS and external changes EZs

Question 2

What is a circadian rhythm?

Answer 2

A type of biological rhythm subjected to a 24- hour cycle which regulates processes such as the sleep/wake cycle

Question 3

What are circadian rhythms?

Answer 3

Circadian rhythms are driven by body clocks found in the cells of the body which are synchronised by the SCN (in the hypothalamus).

• This rhythm needs to constantly be resort by light to allow bodies to be in synchrony with the outside world

Question 4

What enables the sleep /wake cycle to be maintained?

Answer 4

• Light and darkness EZs are the external cues that determines when we sleep or awake
• Our homeostatic system tries to enable homeostasis - also note changes energy dips (EPs)
• Even in the absence of external cues, the internal circadian clock is 24-25 hrs
• This means internal and external cues combine to enable us to keep rhythm and adjust to changes

Question 5

Cycle example - core body temperature

Answer 5

• At its lowest at 36c at 4 am and highest at 6pm 38c → normal circadian rhythm sleep occurs when temperature drops and temp rise in last hours of sleep creating feeling in alertness

Question 6

Siffre - research into circadiun rhythms procedure

Answer 6

• 1972 French cave explorer spent 6 months in a cave
• No natural light → electricity though
• Biological clock allowed to free run
• Wired up to record bodily functions / telephone to outside world and monitored on a camera

Question 8

Siffre - research into circadiun rhythms Findings

Answer 8

Erratic sleep - wake cycle at first - settled to 25 hrs

Question 9

Siffre - research into circadiun rhythms - conclusions

Answer 9

we do have an internal mechanism EP that regulates are sleep / wake cycle but it shifts if we do not have EZ to reset it →
* When the biological clocks are left to free run able to maintain a rhythm on their own.

Question 10

Strengths - circadian rhythms

Answer 10

• RWA-
  Development of chronotherapeutics - timing of drug therapy

The timing of drug treatment has impact on the treatments success
Drugs can be taken hours before release in order to treatment effectively

• Practical ability
  From research it has been identified the adverse consequences that can occur as a result of disruption to cycles

Night workers in shift work - experience period of reduced concentration at 6 in the morning

Found link between shift work and poor health - more likely to get cardiovascular issues as stress of sleeping

Have economic implications of how to manage worker productivity

Question 11

Limitations - circadian rhythm

Answer 11

• Psychologists are critical for use of artificial lights
  These may affect the free-running circadian rhythm by acting as an AZ
  Decreasing the internal validity of the research
• Individual differences
  Length of cycle can vary - 13-65 hours

Duffy - identified early risers Larks and wake later Hours
Explanation
Larks- Mutation of hPer2 gene -
Larks
Owls - mutation hPer3gene

• Studies of the sleep/wake cycle involve smaller groups of ppt
  Single case studies
  Lack generalizability ie siffre 60 may have an slow body clock as older