Biological rhythms

?
  • Created by: cieran32
  • Created on: 22-10-18 14:53

Biological Rhythms vary in length

Circadian rhythms- have cycles that genrally occur once every 24hours. For example, we will usually go through the sleep-wke cycle once every day.

Infradian rhythms- have cycles that occur less than once everyday.  For example, the menstrual cycle. Sabbagh and Barnard (1984) found that when women live together they become sychronised- due to pheromones.

Ultradian rhytms- have cycles that occur more than once every 24hours. For example the sleep cycle with the  stages of sleep.

1 of 7

Biological Rhythms are regulated by internal and e

Endogenous Pacemakers

  • Some aspects of our biological rhytms re set by genetically determined biological structures and mechanisms within the body
  • The suparchiasmatic nucleus (SCN), part of the hypothalamus, seems to act as an internal clock to keep the body on an approxiamte 24- hour sleep- waking cycle.
  • it is sensitive to light and regulates the pineal gland, which secretes melatonin-  a hormone which seems to induce sleep. When there is less light, more melatonin is produced. When there is more light, secretion is reduced and wlking occurs.
  • Menaker et al (1978) lesioned this tructure in hamsters-their sleep- walking cycle was disrupted

Exogenous Pacemakers

  • These are influence outside of the body that act like a prompt, which may trigger a biological rhythm
  • Light is the most important Zeitgeber- (time giver). Siffre (1975) spent six months in a cave - his sleep - waking cycle extended from a 24hour cycle to 25-30hour cycle. 
2 of 7

Endogenous and Exogenous Factors Interact

  • They ineract to regulate timing of our biological rhytm 
  • In some cses, endogenous factors may completely determine a cycle. Pengelly and Fisher (1957) found that squirrels will hibernate even when kept in laboratory conditions very different from their natural environment.
  • However, many animals can react more flexbility , espeically humans who are able to adapt to their surrondngs we can make ourselves stay awake and change the environment to suit our needs
  • Cultural Factors are also important, For exmple, Eskimos often live in permanent daylight or permanent night-time but cn maintain regular daily sleep cycles- so the cycle can't just be determined by levels of light acting on the pineal gland.
3 of 7

Disrupting biological Rhythms can have Negative Co

When endogenous pacemakers become out of line with exogenous Zeitgebers, it can disrupt the sleep- wake cycle. 

Jet Lag

  • when you travel you feel tired later or earlier depnding on how many hours behind or infront you are and it seems easier to adapt by staying awake
  • it can take around a week to fully synchronise to a new time zone. Wegman et al (1986) found that travelling east to west (phase delay) seems easer to adapt than west to east (phase advance)
  • Schwartz et al  (1995) found that baseball teams from east got better results travelling to west than teams in west playing in est. 
4 of 7

Disrupting biological Rhythms can have Negative Co

Shift Work

Czeisler et al (1982) studied workers at a factory whose shift patterns appeared to cause sleep and health problems. The reserchers recommended 21 day shifts (allowing more time for workers to adapt) and changing shifts forward in time (phase delay). After implementing the changes productivity and job satisfaction increased. 

5 of 7

Disrupting biological Rhythms can have Negative Co

Shift Work

Czeisler et al (1982) studied workers at a factory whose shift patterns appeared to cause sleep and health problems. The reserchers recommended 21 day shifts (allowing more time for workers to adapt) and changing shifts forward in time (phase delay). After implementing the changes productivity and job satisfaction increased. 

6 of 7

research on biological Rhythms has limitations

  • Findings from animal studies can't be accurately generalised to humans - humans have greater adaptbility
  • Studies that have deprived humans of natural light have still allowed artificial, which may give many of the benefits of natural light- this reduces validity of these studies.
  • Individual differences play a part as some people feel more alert in mornings and some later on
7 of 7

Comments

No comments have yet been made

Similar Psychology resources:

See all Psychology resources »See all biopsychology resources »