The analysis of motivational systems underlying temporal organisation in animal behaviour has relied primarily on two conceptual functional frameworks: Homeostasis and biological clocks. Homeostasis is one of the most general and influential concepts in physiology. Walter Cannon introduced homeostasis as a universal regulatory principle which animals employ to maintain constancy of their ‘internal milieu’ in the face of challenges and perturbations from the external environment. Cannon spoke of “The Wisdom of the Body”, the collective of responses designed to defend the ideal internal state against those perturbations.

The present review summarizes the prevalence, clinical phenomena, and pathogenesis of sleep and wake disorders in shift workers. Insomnia and hyper-somnolence occur in more than 50% of shift workers, mainly in association with the night shift. Circadian rhythm disruption is the major determinant of these disorders. Furthermore they are frequently associated with psycho-social problems and somatic diseases. In more than 20% of the shift workers problems are so pronounced, that they fail to adapt to the rotating schedules. This is defined as ‘shift maladaptation syndrome’.

The present review deals with preventive and treatment strategies for sleep and wake disorders, and the other problems of shift workers. Management must take into account the direction, speed and other parameters of the rotation schedule. Good sleep-wake hygiene may alleviate the problems. Further, additional napping may compensate – at least partially – for sleep deprivation and fatigue. Hypnotics must be avoided as much as possible. Finally, new techniques for manipulation of circadian rhythms are discussed: light, melatonin and benzodiazepines.