《cycle of activity》阅读赏析

We all know that the normal human daily cycle of activity is of some 7-8 hours sleep alternation with some 16-17 hours wakefulness and that, broadly speaking, the sleep normally coincides with the hours of darkness. Our present concern is with how easily and to what extent this cycle can be modified.

The question is no mere academic one. The ease, for example, with which people can change from working in the day to working at night is a question of growing importance in industry where automation calls for round-the-clock working of machines. It normally takes from five days to one week for a person to adapt to a reversed routine of sleep and wakefulness, sleeping during the day and working at night. Unfortunately, it is often the case in industry that shifts are changed every week; a person may work from 12:00 midnight to 8:00 a.m. one week, 8:00 a.m. to 4:00 p.m. the next, and 4:00p.m. to 12:00 midnight the third and so on. This means that no sooner has he got used to one routine than he has to change to another, so that much of his time is spent neither working nor sleeping very efficiently.

The only real solution appears to be to hand over the night shift to a number of permanent night workers. An interesting study of the domestic life and health of night-shift workers was carried out by Brown in 1957. She found a high incidence of disturbed sleep and other disorders among those on alternating day and night shifts, but no abnormal occurrence of these phenomena among those on permanent night work.