Disrupting biological rhythms - technological advances, including electric lighting and jet travel have altered our habits, creating a 24 hour culture which can sometimes desynchronise our body clocks from the main exogenous zeitgeber, light. If biological rhythms are forced to change quickly problems can arise such as poor attention, slow reaction times and impaired reasoning skills. The two most obvious examples of this are shift work and jet lag.
Jet Lag: When we travel across time zones the body's internal body clock (endogenous pacemakers) becomes out of sync with external cues (exogenous zeitgebers). This can lead to fatigue, insomnia and a weakened immune system
- Phase advance vs phase delay: Travelling from West to East is phase advance, travelling from East to West is phase delay. Coren (1996) found that phase delay is easier to adjust to than phase advance.
- Phase delay: (East to West) the body clock is ahead of local time, have to wait for time to catch up. This means your body would think it was bed time when external cues are telling you it's the middle of the day, so you would have to keep yourself stimulated until it was local night time.
- Phase advance: (West to East) the body clock is behind local time. This means your endogenous clock would have lost time, and you'd have to force yourself to go to sleep when your body thinks it's still the middle of the day.
- Schwartz et al (1995) studied results of baseball teams on west and east coasts of America, (3 hour time difference). Teams from the east travelling to play games in the west (phase delay) won significantly more games than the teams from the west when they had the travel to play games in the east (phase advance). This supports the idea that it is easier to adjust to phase delay than phase advance.
- A problem with this research is that teams from the east coast may have simply been better players, or other variables may…