Disruption Of Biological Rhythms

Question 0

Klein et al: ES (Jet lag 1-6)

Answer 0

• Found that E to W passengers took 1 day f complete readjustment
• W to E took 6 days for complete readjustment.
• did not matter if they were travelling home or away from home.
• Suggests more difficult adjusting to phase advance than Ph delay.

Question 1

Jet lag

Answer 1

• Occurs when individual crosses time zones; disrupts CR/UR.
• Large difference between your EP and EZ (local time destination).
• Disrupt BR = psych/physio symptoms (fatigue, headache, stomach disturbances. BT also be disrupted; desynchronised from S/W cycle. This ^ feelings of disorientation.
• West to east ^difficult to adjust as day shortened (phase advance). -East to West induces a phase delay resembles going to bed later.
• Body tries to be alert and active when we would usually be tired.

Question 2

Recht et al: US baseball 44-37

Answer 2

• Studied the results of U.S. Baseball teams over three years.
• Found teams E2W before game won 44% but those travelling W2E won only 37%, significantly fewer.
• Problem is that R prone to ID between teams as one may have simply been better than others.
• Partly controlled for by the long study period of 3 years meaning the effect of the ev should even out over time.
• Provides support for effects of jet lag indicating theory is robust.

Question 3

Fuller et al: BD (adopting social rhythms)

Answer 3

• determinist bc travellers sleeping beh controlled solely by EP. But R into CR shows this is just not the case.
• //adopting social rhythms and eating/sleeping time of destination country, people may override physiological drives using EZ.
• Fuller et al: A period of fasting followed by eating in destinations time schedule should entrain our BR by adjusting the body clock.
• TF by adapting to changing env circumstances we exercise FW.
• RWA wrt to how flight companies organise meal schedules.

Question 4

Beaumont et al: melatonin RwA

Answer 4

• Evidence melatonin can ^synch speed of CR and reduce jet lag.
• Found that melatonin given at bed time will v symptoms of jet lag. -^knowledge of E body clocks and EZ allow us to understand why JL occurs and to design effective ways of coping with it.
• AT theory is inherently determinist it shouldn’t be looked at as -ve, rather an “informative criticism” as it contributes towards development of new drug based therapy to treat Bio mech behind jet lag.

Question 5

Shift work: circadian trough / health problems

Answer 5

Shift work = major disruption to BR; working when B wants sleep and trying to sleep when the body want to be awake.

• If given enough time our BR can re-program; cope with shift work.
• Many shift workers operating machinery/making decisions at a time when EP completely out of synch with external world i.e Dr.
• Bovin et al “SW exper circadian trough of v alertness between 12 am and 4am, cortisol levels are lowest and BT is at it lowest.
• Chernobyl disaster took place during this phase of shift work.
• FM SW often difficult to sleep, lose avg 2 hrs sleep a day.
• = sleep deprivation = development of health problems i.e. type 2 diabetes, hypertension, CHD, cancer, depression and anxiety.

Question 6

Gold et al: RWA (rotating shifts bad)

Answer 6

• Aware of -ve effects of SW = RWA changing type of shift system.
• Found more problems occur when shifts alternate every few days. -Non-fluctuating shifts (always works nights) v disruptive; get used to one S/Wc. RWA has sig^ QOL of SW minimising disruption to their re-programmed circadian rhythms.

Question 7

Czeisler et al: RS (rotating shift)

Answer 7

• Studied SW; Utah chemical plant. Found ^rate of health problems, sleep difficulties and work-related stress for short shift rotating staff.
• Persuaded to change to phase delay pattern (move shifts forward every time) and to ^ shift rotation from 7-21 days, = ^time to adjust. -After 9 months worker satisfaction and factory output sig^, industrial accidents were at the lowest they’d ever been.

Question 8

Knutsson: 30% heart disease

Kubo: 14052, 4x prostate cancer

Answer 8

There is empirical support for the association between night and rotating shifts and a range of health problems. Knutsson et al found that night shift work increase the risk of developing heart disease by 30% in men and women working shifts for 16-20 years, compared with that found in day workers.
In addition Kubo et al suggested that people working rotating shifts are particularly vulnerable to cancer. They studied 14052 Japanese male workers, controlling for lifestyle factors such as smoking, alcohol consumption, stress and type of work and found that men who worked night shifts were 4x more likely to develop prostrate cancer than men who worked fixed day shifts. This suggests that a disruption to the sleep wake cycle reduces the effectiveness of the immune system, leading to an increase in health problems.