Sleep

Question 1

1st paragraph (disrupting br)

Answer 1

Jet lag can be caused by phase delay, when we gain time, so travel from East to west. This means that you go to bed later than normal and your day is extended.
Phase advance occurs when we lose time so travel from west to east. This can mean that you have to get up when you are used to being asleep (in a circadian trough). As a result, the day is shortened. This is thought to have the worst effect as it takes longer for our pacemaker to resynchronise.

Question 2

2nd paragraph (disrupting br)

Answer 2

Recht et al analysed Major League Baseball results in the US over a 3 year period and found that baseball teams won 37% of their games after travelling west to east and 44% after travelling east to west. This supports the idea that travelling west to east will have a worse effect.
*study may present misleading findings as it does not take into account the ability of the individual teams. Therefore may lack internal validity as it is not truly measuring the effects of jet lag on performance but rather the ability of the team.i

Question 3

3rd paragraph (disrupting br)

Answer 3

Shift work requires workers to go against their natural bodily rhythms by working when they would normally be sleeping. This can be a particular problem as night workers are often required to be awake and alert at a time when their endogenous pacemakers and exogenous zeitgebers instruct their bodies to be asleep.

Lack of sleep can lead to decreased alertness during their shifts as between midnight and 4am cortisol and core body temperatures are lowest.

Question 4

Evidence to support (disrupting br)

Answer 4

Knutsson found that individuals who worked shifts for more than 15 years were 3 times more likely to develop heart disease showing that there are negative consequences on a persons health when biological rhythms are disrupted. This supports the idea that shift work can have negative effects on the cardiovascular system.

Question 5

IDA (disrupting br)

Answer 5

Shift workers are vital in our society. Research in Utah has shown that negative effects of shift work can be avoided using certain techniques which go with the body’s natural rhythms. They demonstrated that when shifts rotate forwards, it takes advantage of the body’s preference for 25 hour cycle. Using the new schedule, workers enjoyed better health and productivity rose by 22%.

Question 6

Intro (disrupting br)

Answer 6

Jet lag causes desynchronisation of internal rhythms, as there is conflict between our ep and ez. Our biological rhythms are not equipped to cope with sudden changes, e.g. Jet lag. It is estimated the SCN takes several cycles to fully resynchronise to these changes.