Chapter 15 



THE SLEEP-WAKEFULNESS CYCLE OF SUBMARINE PERSONNEL 



NATHANIEL KLEITMAN 

 University of Chicago 



One aspect of the problem of sleep aboard 

 submarines is related to habitability and re- 

 volves around the space and comfort of sleep- 

 ing accommodations. However, there is the 

 much wider conception of sleep as one phase 

 of the sleep-wakefulness cycle, which touches 

 upon emotional stability and adjustment, as 

 well as efficiency in performing the many 

 different tasks assigned to the submarine 

 personnel. The sleep-wakefulness cycle is 

 more closely related to the problems of hu- 

 man engineering than to those of habitabil- 

 ity, and it is proposed to devote the major 

 portion of this discussion to the distribution 

 and timing of watches, the hours of meals 

 and recreation, the fixity and variability of 

 daily schedules, and the bearing all these fac- 

 tors have on well-being and efficiency of the 

 individuals concerned. 



In most civilian occupations gainfully em- 

 ployed persons work between the hours of 

 8 a.m. and 6 p.m. Their daily routine, and 

 that of their families, is built around these 

 conventional working hours. Getting-up 

 time is between 6 and 7 a.m.; after-work 

 hours, following the evening meal, are de- 

 voted to recreation; and bedtime is 10 p.m. 

 to midnight. Shops, offices, and schools are 

 open during the usual business hours. Even 

 when the breadwinners work at odd hours 

 (in fire and poUce departments, transporta- 

 tion, theaters, night restaurants, newspapers, 

 two- or three-shift factory operations), other 

 members of their families follow the com- 

 munity pattern of living. By repeatedly 

 observing a definite socially-accepted sched- 

 ule of hours for work, play, meals, and sleep, 

 one develops a diurnal cycle of sleep and 

 wakefulness, as a result of which it is easier 



329 



to remain alert during certain hours of the 

 day and harder to keep awake during the 

 fraction of the 24-hour period usually de- 

 voted to sleep. 



There is nothing physiologically compel- 

 ling about the 24-hour alternation of sleep 

 and wakefulness. The cycle stems from the 

 astronomical fact of the succession of day 

 and night, to which the social organization 

 of community life is adapted by preference. 

 The individual, however, is born into a so- 

 ciety which already possesses a fairly fixed 

 schedule of activities, and is made to "swing 

 into step" with his family and community. 

 Shifts in the timing of the individual's rou- 

 tine occur when he moves into a new time 

 zone, differing by 1 to as many as 12 hours 

 from the old, and in community schedules, 

 through sunmier and winter times ("day- 

 light saving" and "standard") 



A very simple test of the degree of adapta- 

 tion of the individual to the 24-hour cycle 

 is the fLxity of the diurnal body temperature 

 curve. It has been known for a long time 

 that the body temperature of so-called 

 warm-blooded or homoiothermal animals is 

 not really constant, but may show fluctua- 

 tions of one or more degrees F., without 

 necessarily bringing into play thermostatic 

 physiological adjustments. Among these 

 fluctuations, the most regular one is the 

 diurnal body temperature curve. This 

 curve is not present at birth, but is estab- 

 fished and maintained first by the imposi- 

 tion, and later by free acceptance, of the 

 family and community pattern of living. 

 The curve can be shifted, inverted, distorted, 

 shortened, or lengthened, by following a new 

 schedule of activities for a certain number 



