4(^ J. LiNmiAiu). 



valions during a week when I was on the night-watch. Taken on 

 the whole the curve exhibits rather a chaotic appearance; the 

 periods for sleep are unequally long and unequally distributed; the 

 average of the curve is fairly low. It is seen, however, that the 

 lowest values occur in the night, which appears even more distinctly 

 from curve 2, a portion of the former and drawn on the usual scale. 

 This resembles by not so little the night-watch curves of Benedict, 

 where as in my case the lowest temperatures occurred in the night; 

 for both cases it holds good that the individual concerned partook 

 of his meals in the day-time together with other people, and for 

 this reason alone a fall of temperature must be expected towards 

 night; in the day-time the temperature is also inclined to fall be- 

 tween the meals. Like most other night-watches I slept less than 

 under ordinary conditions, not to be quite out of touch with other 

 people, so that I often felt sleepy for periods, especially in the night 

 when I passed most of the time with sedentary work. It was only 

 towards the morning that I found occasion for some bodily exercise, 

 lighting the fire in the stove etc.; a rise in the temperature is there- 

 fore found from 4 to 6 in the morning. But there is lastly one 

 fact, probably unnoticed hitherto or at any rate not deservedly 

 estimated in this connection, viz. the psychical factor of the night-time. 



I shall not venture here on any discussion of the psychology of 

 the night, but only call attention to the fact, that the night-time 

 undoubtedly has a peculiar effect upon one's general state of mind 

 owing to Ihe stillness, solitariness and various other circumstances, 

 and this changed, psychical condition reacts on all one undertakes. 

 Every strong or sudden noise is disagreeable, and involuntarily one 

 tries to avoid all such things; the movements become gliding and 

 noiseless, resembling those of other night-animals, and are much 

 less definite than in the day-time. A round in the night will there- 

 fore fail to raise the temperature like a corresponding walk in the 

 day-time. And one is never sitting so still as in the night; the 

 leaves in one's book are turned almost without touching them. 



The view that this factor is of essential importance for the form 

 of the curve of temperature in a night-watch is strengthened by 

 some measurements made on a "night-watch in the day". At a 

 period during the winter of 1907, on which more details will be 

 given below, we reversed day and night, so that we were up in the 

 night and slept during the day. The night-watch concerned con- 

 tinued his mode of life as regards sleep and waking, though we 

 others "reversed". He took his sleep all at one lime, as displayed 

 by the curve (curve 3 on fig. 7), about НУ -j hours, so that he had no 

 reason to be sleepy in Ihe "night"; nevertheless, his curve is very 



