Body temperature Χ2 value φ P value Low body temperature (n = 35) Normal temperature (n = 191) n % Adjusted residual n % Adjusted residual Breakfast (n = 226) I eat breakfast every morning. 28 12.39 −2.4 177 78.32 2.4 5.63 −0.16 0.02* I sometimes do not eat breakfast. 7 3.10 2.4 14 6.19 −2.4 Bowel movement (n = 226) I have bowel movement every day. 18 7.96 −1.0 116 51.33 1.0 1.06 −0.07 0.30 I do not have bowel movement every day. 17 7.52 1.0 75 33.19 1.0 School meal (n = 226) I always eat a full school meal. 30 13.27 3.1 111 49.12 −3.1 8.46 0.21 0.00a)*** I sometimes leave part of a school meal. 5 2.21 −3.1 80 35.40 3.1 Snack (lunch to dinner) (n = 226) I eat a snack four days or more a week. 13 5.75 −0.1 73 32.30 0.1 0.02 −0.01 0.90 I eat a snack less than three days a week. 22 9.73 0.1 118 52.21 −0.1 Snack (dinner to fall asleep) (n = 226) I eat a snack four days or more a week. 1 0.44 −1.1 15 6.64 1.1 0.49 −0.07 0.48a) I eat a snack less than three days a week. 34 15.04 1.1 176 77.88 −1.1 Exercise (n = 226) I exercise three or more days a week. 26 11.50 −0.6 150 66.37 0.6 0.31 −0.04 0.58 I exercise less than two days a week. 9 3.98 0.6 41 18.14 −0.6 Cram school (n = 226) I am going to cram school. 16 7.08 −0.2 90 39.82 0.2 0.02 −0.01 0.88 I am not going to cram school. 19 8.41 0.2 101 44.69 −0.2 PSQI (n = 226) PSQI ≥ 6 2 0.88 −0.8 6 2.65 0.8 0.07 −0.05 0.36a) PSQI < 6 33 14.60 0.8 185 81.86 −0.8 Physical strength (n = 225) High 17 7.56 0.4 102 45.33 −0.4 0.13 0.02 0.71 Low 17 7.56 −0.4 89 39.56 0.4 Falling asleep# (n = 177) I could fall asleep quickly. 19 10.73 0.0 134 75.71 0.0 0.00 0.00 1.00a) I had difficulty sleeping. 3 1.69 0.0 21 11.86 0.0 Wake up## (n = 105) I woke up feeling refreshed. 12 11.43 0.3 69 65.71 −0.3 0.00 0.03 1.00a) I was sleepy. 3 2.86 −0.3 21 20.00 0.3