Describe two biological rhythms
Jet lag occurs when individuals cross time zones. This disrupts the natural rhythm of the biological clock. It occurs when there is sufficient discrepancy between internal time and external time. Symptoms include headache, sleep disruptions and gastrointestinal disturbances. Klein, Wegman and Hunt’s found people recover faster from jet lag after flying east to west than in the opposite direction. These findings suggest that it takes the endogenous mechanism and therefore the sleep wake cycle about one day per time zone crossed to recover. Schwartz, Reat, and Lew 1995 analysed the results of American baseball games in relation to weather the teams had to travel east to west or west to east. They found that west coast teams travelling east lost more games that those travelling west.
Shift work causes major disruptions of the biological rhythms because the individual is working when the body wants to be sleeping and awake when the body wants to be sleeping. Akerstedt showed that people on shift work slept 1-4 hours less than they could normally at night. He also showed that they had a particular deflect in REM sleep and so if REM sleep has a particular function then this function would also show a deflect.