Toshio Nakano

Nineteen-hour variation of postural sway, alertness and rectal temperature during sleep deprivation.

Nineteen‐hour variation of postural sway, alertness and rectal temperature during sleep deprivation were studied. Alertness decreased gradually at night and remained low until morning. Postural sway in the eyes‐closed condition increased during early morning. In six of the eight subjects the greatest sway was observed during the 3‐h period when rectal temperature was at its minimum. It is suggested that unbearable sleepiness during sleep deprivation will give rise to measurable impairment of postural balance especially during the time zone of temperature nadir.

Bright light treatment for sleep–wake disturbances in aged individuals with dementia

Treatment using bright light exposure was carried out on six aged subjects with dementia in two nursing homes. Sleep logs were recorded by the staff. Bright light treatment was applied in the late morning every day. The %sleep in the lights‐out period and/or the %wake in daytime increased in three subjects. In the other three subjects, sleep onset time was advanced. In all subjects abnormal behavior episodes around the lights‐out time tended to be reduced. These results suggest that bright light treatment is effective in improving the sleep–wake disturbances of aged individuals with dementia.

SLEEP IMPROVEMENT BY LIGHT IN A DEMENTED AGED INDIVIDUAL

Abstract We administered daily morning bright light exposure in two separate periods to a demented aged subject in a nursing home and analyzed the sleep pattern changes from the sleep diary over 6 months. In the first light exposure period, the ratio of sleep time in night hours increased and maintained a higher value throughout the period than the previous baseline. After stopping the light exposure, the sleep pattern of the subject deteriorated. Resuming the light exposure reproduced similar sleep pattern changes. These results suggest that morning bright light exposure provides a better environment for aged persons to maintain a regular sleep‐wake pattern.

Effects of moderately bright light on subjective evaluations in healthy elderly women

Eight healthy elderly women aged 56–72 years (mean age: 67.4 years) participated in this study. They were exposed to moderately bright light (1000 lux) for 1 h in the morning every 6 days in their homes. Moderately bright light improved self evaluations for alertness, mood, motivation, happiness, refreshment, concentration and appetite after the second exposure to the light. Sleep maintenance, anxiety and integrated sleep feeling also improved after the fourth exposure to the light. The phase of rectal temperature rhythm did not change in a moderately bright light condition. These results suggest that bright light influences sleep quality and self evaluations without changing the biological rhythm phase.

Use of an infrared sensor system to take long-term bedside measurements of rest–activity patterns in the elderly with dementia

Abstract In order to study long‐term rest–activity patterns of elderly residents in care facilities, an infrared sensor system was developed. This sensor system detects a resident’s presence or absence from their bed and their activity with little inconvenience. Using this system, the rest–activity patterns of two elderly people with dementia was assessed over a period of 3 months. For both subjects, frequent activity peaks and absences from their beds were often observed during the night. Such a sensor system will be useful for evaluating the sleep–wake rhythms of people with sleep disorders.

Effects of short duration morning bright light in healthy elderly subjects. I:Subjective feeling and ophthalmological examinations

Abstract Seven aged subjects aged 61–78 years were exposed to 6000 lx bright light for 30 min during morning hours at their homes for 1 week. Visual analog scale was recorded before bedtime and after rising to assess subjective feelings. Ophthalmological examinations were made before and after light exposure, to exclude pre‐existing ocular disorders and to detect ocular damage. Furthermore, ocular fatigue was self‐evaluated immediately before and after exposure. Visual analog scale results indicated that alertness reduced significantly before bedtime. Ophthalmological abnormalities were not found after exposure. These findings suggest that short duration morning bright light exposure reduces night‐time vigilance.

Temporal order of sleepiness, performance and physiological indices during 19-h sleep deprivation

Nineteen‐hour variation of subjective sleepiness, performance and physiological indices were assessed during sleep deprivation. Longitudinal data of each index had its characteristic curve through which the values changed from day level to night level. A comparison of the time when each curve crossed its mid‐range (50% value of its range) showed that those of subjective sleepiness and heart rate were significantly earlier than those of tracking error and coefficient of variation of R‐R interval (CVR‐R), P < 0.01. That of rectal temperature was located at between 1:00 and 4:00 am. These temporal relationships were reproducible under two lighting conditions. These results will be useful in considering the occurrence of human errors by night‐time workers in the early morning.

Measurement of human behavior in a daily life based on the understanding of biological rhythm

We concentrate on the rhythms of daily life that are basic for the safety and health of elderly people, and develop a measurement evaluation technology. In this report, we introduce a technology that measures body movement in bed by using an infrared sensor system to evaluate the quality of sleep. In addition, we classify daily life behavior from the viewpoint of QOL (quality of life) into about 15 kinds of body activities, and provide standard behavior for each body activity. We introduce technology that measures body activity in daily life by using acceleration sensors.