ABSTRACT
This chapter looks at what happens when bodily rhythms are disturbed. It provides reader with evidence for discussing sleep and dream states and the theories of sleep and dreaming. Akerstedt showed that people on shift work slept 1-4 hours less than when they could sleep normally at night. Errors or mistakes, known as performance deficits, have been linked with disturbances in our bodily rhythms, especially our sleep cycle. Shift work, with its disruption of the daily rhythm, has the strongest links to performance deficits. When there is a discord between internal 'time' and external cues a person may experience negative effects, as in seasonal affective disorder, shift work and jet lag. Shift work requires changes in a person's sleep-wake rhythm, so it is out of synchrony with the environment. The effects of disrupted bodily rhythms may also be observed in pre-menstrual syndrome. When bodily rhythms are disturbed, there may be associated performance deficits.
