The effects of inadequate sleep habits in children on their health: From the viewpoint of shortened sleep and the eveningness preference

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 12610098
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 実験系心理学
• Research Institution: Notre Dame Seishin University
• Principal Investigator: ISHIHARA Kaneyoshi Faculty of Human Life Scinences, Department of Child Welfare, Professor, 人間生活学部, 教授 (80159756)
• Co-Investigator(Kenkyū-buntansha): TADA Shimako Child Clinic Institute, Assistant, 助手 (40309597)
• Project Period (FY): 2000 – 2002
• Keywords: Sleep habits / Sleep restriction / Eveningness preference / Psychosomatic fatigue / Daytime sleepiness / Circadian rhythm / Body temperature

Research Abstract

The purpose of the present study were to investigate the effects of inadequate sleep habits among children including shortened sleep and eveningness preference on their psychosomatic symptoms. This study consisted of two experimental studies, a field study, and questionnaire- based study from four elementary schools
Experiment 1 The effect of sleep amount on daytime sleepiness and development of body temperature rhythm were investigated. Three children were longitudinally evaluated for three conditions: control (habitual bedtime and risetime), sleep extension by an advanced bedtime, and sleep reduction by a delayed bedtime. A sleep latency test was conducted five times for each condition at 2- h intervals from 10.00 hours. In the laboratory, oral temperature was measured at 1- h intervals from 10.00 to 19.00 hours; at home it was also measured at risetine and hourly from 21.00 to bedtime. The results showed that the effects of sleep loss increased sleepiness at 10.00 hours and at 18.00 hours. The phase delay of temperature was found in all subjects even after five years old. These results suggested that the intensity of morning sleepiness might become a useful measure which reflects sleep loss and that the establishment of body temperature phase might be after 5 years old
Experiment 2 Experiment 2 was conducted with the procedure as Experiment 1 except the number of the subjects was 10 high school students instead of 3 children. When the sleep sufficient group and a sleep lack group were compared, more increase in sleepiness in the morning (10.00 hours) was found in the sleep lack group. The phase delay of temperature rhythm was also observed in the lack group
Field study Daily rhythm of oral temperature and sleep habits were examined in 101 elementary school children (grades 4 and 6) and 140 junior high school students (grades 1 and 3). There were significant age effects in circadian parameters (mesor, amplitude and acrophase) and sleep parameters (bedtime, risetime and sleep length). Mesor and amplitude decreased and acrophase became delayed for 0.7 hours as age increased. Although the bedtime of the ninth graders was delayed by two hours later than that of the fourth graders, risetime of the ninth graders became delayed by only 0.5 hours later. The result showed that the ninth graders slept 1.6 hours shorter than the fourth graders. Considering the delay of temperature acrophase, it was suggested that the delay of bedtime hardly influences the acrophase
Furthermore, when the early bedtime group and the delayed bedtime group were compared, the score of psychosomatic symptoms in the delayed bedtime group was higher than that in the early bedtime group
Qeuastionnaire- based study This study was to investigate to what extent inadequate sleep habits influenced psychosomatic symptoms (stress responses). Although only the relationship between psychological stressors and psychosomatic symptoms has been studied in conventional stress research, the result of the study indicated that inadequate sleep habits might be regarded as stressors. A sleep habits questionnaire, psychological stressors questionnaire, and a stress response questionnaire were administered to 461 elementary school childres (5th and 6th graders). After examining the effects of inadequate sleep habits on the stress responses, it was found that inadequate sleep habits influenced stress responses as well as psychological stressors