Seasonal aspects of sleep in the Djungarian hamster

BMC Neuroscience

Table 2 Seasonal differences in duration and frequency of vigilance state episodes.

	Hamsters in winter physiological state			Hamsters in summer physiological state
	8-h L	16-h D	24 h	8-h L	16-h D	24 h
Episode duration (min)
Waking	6.35 ± 0.72	6.27 ± 0.47	6.21 ± 0.42	5.26 ± 0.47**	7.57 ± 0.81	6.75 ± 0.62
NREM sleep	7.54 ± 0.31	7.39 ± 0.38	7.43 ± 0.35	7.94 ± 0.36	7.15 ± 0.31	7.40 ± 0.26
REM sleep	1.73 ± 0.07	1.67 ± 0.07	1.69 ± 0.06	2.08 ± 0.17***	1.64 ± 0.09	1.82 ± 0.12
Episode frequency (# per h)
Waking	4.15 ± 0.40	4.29 ± 0.29	4.25 ± 0.30	3.98 ± 0.25	4.20 ± 0.41	4.13 ± 0.34
NREM sleep	4.48 ± 0.19	4.15 ± 0.23	4.26 ± 0.19	4.56 ± 0.19*	3.90 ± 0.23	4.12 ± 0.19
REM sleep	3.29 ± 0.20***	2.65 ± 0.15	2.86 ± 0.15	3.52 ± 0.27****	2.36 ± 0.14	2.75 ± 0.16

Mean values (± SEM) for duration (minutes) and frequency (number of episodes per hour) of vigilance state episodes for the light (L) and dark (D) period (LD 8:16 h), and for the entire 24 h recording in the winter physiological state (n = 10) and summer physiological state (n = 11). L vs. D: *p < 0.05, **p < 0.01, ***p < 0.005, ****p < 0.001, two-tailed paired t-test. For n = 6: 24-h REM sleep episode duration: winter vs. summer, p < 0.05, L vs. D in summer, p < 0.01; REM sleep episode frequency: L vs D p < 0.05 both in winter and summer.

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