856 PERIODIC FUNCTIONS IN MAMMALS 



Shcherbakova's experiments was achieved with different ease, most 

 easily by changing night to day, with most difficulty by creating 2 

 'days' and 2 'nights' during 24 hours. In the first case, a complete 

 change of 24-hour periodicity was achieved by 7 to 8 days, in the 

 second on the 14th to 15th day." 



The data of Fig. 26a reveal that in man, as well as in the mouse, 

 the timing of rhythms can be shifted within the 24-hr period, by a 

 changed routine, if one adheres to the latter for a sufficient period of 

 time. While Fig. 26a demonstrates shifts of rhythms in blood eosino- 

 phils and rectal temperature. Fig. 27 shows the feasibility of shift in 

 at least one type of convulsive periodicity of man (Halberg, Halberg, 

 and Bittner, 1955; Halberg, Halberg, and Gully, 1953). 



The question may now be explored whether the shift times of these 

 rhythms are the same. A statistical analysis summary in Table I 



Table I. Relation of 24-hr Periodicity in Body Temperature to That in Number 

 of Eosinophils; Correlation Coefficients (r) and Their Significance (P) 



° D = active by da}-; N = active b\' night. 



'' Note lack of correlation during shift in routine. 



seems pertinent in this connection. It can be seen that rectal tempera- 

 ture and blood eosinophils show a significant negative correlation 

 (under standardized conditions) on long-maintained routines, whether 

 they involve activity by day or by night. At 2 days following the 

 institution of a shift, however, this correlation is lost. Among other 

 possible explanations, these findings may perhaps be interpreted as 

 indicative of different shift-times with respect to the two rhythms 

 studied. 



Figures 28 and 29 show data on two groups of human volunteers 

 obtained in an experiment involving a 90° shift in routine. The 



