Acknowledgments
We thank Maiko Fukasawa (National Center of Neurology and Psychiatry), Evelyn Bromet (Stony Brook University), Kenneth E. Nollet (Director, Department of International Cooperation), and Teizo Fujita (Professor Emeritus, Fukushima Medical University) for their helpful advice. The Fukushima Health Management Survey Group Chairpersons: Masafumi Abe (Director General, Radiation Medical Center for the Fukushima Health Management Survey), Shunichi Yamashita (Vice Director, Radiation Medical Center for the Fukushima Health Management Survey), Kenji Kamiya (Vice Director, Radiation Medical Center for the Fukushima Health Management Survey), Seiji Yasumura (Vice Director, Radiation Medical Center for the Fukushima Health Management Survey), Makoto Akashi (National Institute of Radiological Sciences), Kazunori Kodama and Kotaro Ozasa (The Radiation Effects Research Foundation), and Hirooki Yabe (Chairman of Mental Health Survey, Radiation Medical Science Center for the Fukushima Health Management Survey). Participating Expert Committee Members, Advisors, and Staff of the Mental Health and Lifestyle Survey of the Fukushima Health Management Survey: Ohtsura Niwa, Akira Ohtsuru, Shiro Matsui, Shin-ichi Niwa, Yasuto Kunii, Hajime Iwasa, Yoko Nakayama, Misao Ohta, Aya Goto, Mitsuru Hisata, Norito Kawakami, Mitsuaki Hosoya, Mayumi Harigane, Akiko Yagi, Yu-ichi Oikawa, Yuki Ueda, Naoko Horikoshi, Yu-ya Kashiwazaki, Tsuyoshi Takeda, Tetsunobu Hata, Hiroyuki Sugimoto, Yukiko Itoh, Yuko Hino, Keisuke Hiyamizu, Kuni Sugano, Suzuko Yasuhara, Shidu Igarashi, Ai Kawamura, Aiko Matsuda, Mariko Hara, Yuriko Kimura, Yuki Kumasaka, Natsumi Sasaki, Miho Otoji, Ryoichi Kurosawa, Senta Fujii, Misari Oe, Zhang Wen, Hironori Nakano and Fumiko Mori. The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the national “Health Fund for Children and Adults Affected by the Nuclear Incident”.
Table 1.
Baseline characteristics of participants aged 4–6 years by sleep time.
Table 1.
Baseline characteristics of participants aged 4–6 years by sleep time.
| Sleep Time (h/day) | p Value a |
---|
<9 | 9 | 10 | ≥11 |
---|
Participants (n) | 191 | 1368 | 1530 | 294 | |
Female (%) | 51.3 | 48.6 | 49.5 | 51.7 | 0.742 |
Mean age (years) (SD) | 5.2 (0.8) | 5.1 (0.8) | 4.9 (0.8) | 4.7 (0.8) | <0.0001 |
Mean SDQ (SD) | 13.1 (6.4) | 11.7 (5.6) | 11.7 (5.7) | 12.0 (5.7) | 0.012 |
Current state of health (%) | | | | | |
Very good or good | 47.1 | 55.1 | 57.8 | 51.0 | 0.054 |
Normal | 51.3 | 43.4 | 40.3 | 47.3 | |
Poor or very poor | 1.6 | 1.6 | 1.9 | 1.7 | |
Napping time (%) | | | | | |
None | 44.4 | 56.7 | 71.8 | 82.6 | <0.0001 |
<1 hour/day | 2.7 | 1.8 | 1.8 | 1.0 | |
1−2 hours/day | 25.9 | 22.5 | 16.5 | 11.3 | |
≥2 hours/day | 27.0 | 18.9 | 9.9 | 5.1 | |
Tsunami experience (%) | 8.4 | 9.7 | 9.4 | 10.2 | 0.914 |
Nuclear reactor accident experience (%) | 39.3 | 33.9 | 34.3 | 39.1 | 0.188 |
Evacuation to other prefectures (%) | 15.7 | 27.3 | 39.3 | 47.3 | <0.0001 |
Respondent (%) | | | | | |
Mother | 88.5 | 91.6 | 92.8 | 91.5 | 0.206 |
Father | 10.5 | 7.5 | 5.8 | 7.5 | |
Other | 1.1 | 1.0 | 1.4 | 1.0 | |
Table 2.
Baseline characteristics of participants aged 7–12 years by sleep time.
Table 2.
Baseline characteristics of participants aged 7–12 years by sleep time.
| Sleep Time (h/day) | p Value a |
---|
<8 | 8 | 9 | ≥10 |
---|
Participants (n) | 777 | 2758 | 3322 | 593 | |
Female (%) | 58.6 | 49.5 | 46.5 | 47.7 | <0.0001 |
Mean age (years) (SD) | 12.2 (1.1) | 10.9 (1.6) | 9.7 (1.5) | 9.2 (1.4) | <0.0001 |
Mean SDQ (SD) | 10.4 (6.3) | 10.6 (6.1) | 11.1 (6.2) | 12.2 (6.8) | <0.0001 |
Current state of health (%) | | | | | |
Very good or good | 49.2 | 53.4 | 55.0 | 52.7 | 2 × 10−4 |
Normal | 47.1 | 43.0 | 43.1 | 43.4 | |
Poor or very poor | 3.6 | 3.6 | 1.9 | 3.9 | |
Tsunami experience (%) | 11.6 | 12.4 | 11.4 | 11.3 | 0.618 |
Nuclear reactor accident experience (%) | 42.7 | 41.4 | 37.7 | 40.0 | 0.007 |
Evacuation to other prefectures (%) | 21.9 | 22.5 | 29.7 | 47.9 | <0.0001 |
Respondent (%) | | | | | |
Mother | 86.6 | 89.1 | 88.1 | 89.4 | 0.378 |
Father | 11.3 | 9.2 | 9.6 | 8.9 | |
Other | 2.1 | 1.7 | 2.3 | 1.7 | |
Table 3.
Baseline characteristics of participants aged 13–15 years by sleep time.
Table 3.
Baseline characteristics of participants aged 13–15 years by sleep time.
| Sleep Time (h/day) | p Value a |
---|
<6 | 6 | 7 | 8 | ≥9 |
---|
Participants (n) | 160 | 675 | 932 | 557 | 115 | |
Female (%) | 63.8 | 55.4 | 50.0 | 42.9 | 35.7 | <0.0001 |
Mean age (years) (SD) | 14.6 (0.6) | 14.5 (0.6) | 14.4 (0.6) | 14.3 (0.6) | 14.3 (0.6) | <0.0001 |
Mean SDQ (SD) | 11.9 (6.6) | 9.9 (6.2) | 9.4 (5.6) | 9.9 (6.3) | 12.6 (7.0) | <0.0001 |
Current state of health (%) | | | | | | |
Very good or good | 35.4 | 46.3 | 53.5 | 54.8 | 45.6 | <0.0001 |
Normal | 53.2 | 48.1 | 42.8 | 40.3 | 50.0 | |
Poor or very poor | 11.4 | 5.7 | 3.8 | 4.9 | 4.4 | |
Adequate sleep (%) | | | | | | |
Adequate | 10.6 | 22.9 | 44.1 | 71.0 | 70.4 | <0.0001 |
Slightly inadequate | 45.6 | 59.1 | 46.2 | 24.1 | 22.6 | |
Inadequate | 43.8 | 18.0 | 9.8 | 4.9 | 7.0 | |
Tsunami experience (%) | 14.4 | 14.7 | 11.1 | 14.8 | 12.5 | 0.212 |
Nuclear reactor accident experience (%) | 51.0 | 42.6 | 42.7 | 42.8 | 37.5 | 0.254 |
Evacuation to other prefectures (%) | 18.8 | 20.3 | 20.7 | 21.9 | 20.9 | 0.921 |
Respondent of Q1−6 (%) | | | | | | |
Participant | 78.7 | 76.0 | 74.7 | 73.1 | 71.6 | 0.526 |
Proxy | 21.3 | 24.0 | 25.3 | 26.9 | 28.4 | |
Respondent of other questions (%) | | | | | | |
Mother | 87.4 | 83.9 | 84.6 | 84.1 | 79.0 | 0.294 |
Father | 10.7 | 13.7 | 13.4 | 13.0 | 14.9 | |
Other | 1.9 | 2.4 | 2.0 | 2.9 | 6.1 | |
Table 4.
The relationship between sleep time and mental health in participants aged 4–6 years.
Table 4.
The relationship between sleep time and mental health in participants aged 4–6 years.
| Sleep Time (h/day) | p for Trend a |
---|
<9 | 9 | 10 | ≥11 |
---|
Participants (n) | 191 | 1368 | 1530 | 294 | |
SDQ ≥16 (n) | 59 | 328 | 368 | 72 | |
Crude RR | 1.29 (1.02−1.63) | 1.00 (reference) | 1.00 (0.88−1.14) | 1.02 (0.82−1.28) | 0.156 |
Age-sex-adjusted RR b | 1.30 (1.04−1.64) | 1.00 (reference) | 0.98 (0.86−1.12) | 0.97 (0.78−1.21) | 0.053 |
Multivariate RR c | 1.22 (0.98−1.53) | 1.00 (reference) | 1.01 (0.89−1.15) | 0.96 (0.77−1.21) | 0.131 |
Table 5.
The relationship between sleep time and mental health in participants aged 7–12 years.
Table 5.
The relationship between sleep time and mental health in participants aged 7–12 years.
| Sleep Time (hours/day) | p for Trend a |
---|
<8 | 8 | 9 | ≥10 |
---|
Participants (n) | 777 | 2758 | 3322 | 593 | |
SDQ ≥16 (n) | 152 | 552 | 759 | 171 | |
Crude RR | 0.98 (0.83−1.15) | 1.00 (reference) | 1.14 (1.04−1.26) | 1.44 (1.24−1.67) | <0.0001 |
Age-sex-adjusted RR b | 1.02 (0.87−1.20) | 1.00 (reference) | 1.09 (0.98−1.20) | 1.34 (1.16−1.57) | 0.015 |
Multivariate RR c | 0.99 (0.85−1.16) | 1.00 (reference) | 1.12 (1.02−1.24) | 1.30 (1.12−1.51) | 0.002 |
Table 6.
The relationship between sleep time and mental health in participants aged 13–15 years.
Table 6.
The relationship between sleep time and mental health in participants aged 13–15 years.
| Sleep Time (h/day) | p for Trend a |
---|
<6 | 6 | 7 | 8 | ≥9 |
---|
Participants (n) | 160 | 675 | 932 | 557 | 115 | |
SDQ ≥16 (n) | 39 | 109 | 136 | 95 | 36 | |
Crude RR | 1.67 (1.22−2.29) | 1.11 (0.88−1.40) | 1.00 (reference) | 1.17 (0.92−1.49) | 2.15 (1.57−2.93) | 0.580 |
Age-sex-adjusted RR b | 1.67 (1.22−2.30) | 1.11 (0.88−1.40) | 1.00 (reference) | 1.17 (0.92−1.49) | 2.14 (1.56−2.94) | 0.580 |
Multivariate RR c | 1.13 (0.82−1.56) | 0.97 (0.77−1.22) | 1.00 (reference) | 1.19 (0.93−1.51) | 2.04 (1.49−2.77) | 0.015 |