Table 1. Effect of light regimen on survival and life span in male rats. Effect of light/dark regimen on spontaneous tumorigenesis in rats.

Notes: Difference with controls is significant: a, р<0.05. #, in brackets 95% confidential intervals. MRDT, mortality rate doubling time.

Parameters	Light/dark regimen
	LD	NL	LL	DD
Number of rats	57	50	50	51
Mean life span, days	644 ± 34.0	613 ± 32.9	580 ± 35.5	652 ± 32.5
Maximum life span, days,	1045	1046	1005	1017
Mean life span of last 10% survivals, Days	999 ± 11.5	972 ± 22.7	983 ± 13.8	987 ± 13.0
α x 103, days-1	6.06 (5.87; 6.47)	6.70a (6.50; 6.97)	5.19a (4.89; 5.57)	8.31a (8.10; 8.54)
MRDT, days	112.4 (107.1; 118.1)#	103.4 (102.7; 111.6)	133.6a (124.4; 141.7)	83.4a (81.2; 85.5)