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Table 2 Sleep habits on school days and free days in university students in Japan

From: Is the use of high correlated color temperature light at night related to delay of sleep timing in university students? A cross-country study in Japan and China

Japanese High CCT
(n = 275)
Low CCT
(n = 172)
P value
Sleep habits (school days)
  Bedtime 01:13 (0:58) 01:00 (1:04) 0.029 *
 Sleep latency (min) 15.5 (11.8) 15.1 (10.7) 0.668
 Sleep onset time 01:29 (1:00) 01:15 (1:05) 0.026 *
 Wake time 08:02 (1:13) 07:59 (1:10) 0.476
 Midpoint of sleep 04:45 (0:57) 4:37 (0:59) 0.100
 Sleep period time (h) 6.55 (1.14) 6.74 (1.11) 0.186
Sleep habits (free days)
  Bedtime 01:45 (1:13) 01:25 (1:11) 0.003 **
 Sleep latency (min) 16.1 (13.3) 16.1 (12.6) 0.949
 Sleep onset time 02:02 (1:16) 01:41 (1:11) 0.003 **
 Wake time 09:41 (1:27) 09:26 (1:20) 0.052
 Midpoint of sleep 05:51 (1:11) 05:33 (1:08) 0.006 **
 Sleep period time (h) 7.65 (1.33) 7.74 (1.12) 0.495
Social jet lag (h) 1.09 (0.84) 0.94 (0.78) 0.051
  1. Values are means and SD.
  2. Adjusted by age and sex *p < 0.05, **p < 0.01