Young Man Park

Changes in sleep–wake cycle during the period from late pregnancy to puerperium identified through the wrist actigraph and sleep logs

The purpose of this study was to understand the sleep–wake cycle during the period from late pregnancy to about 3 months of postpartum by evaluating the number of actigraphic activities in four women (one multipara and three primi gravidae), and to compare the results with the findings from sleep logs. An irregularity of the sleep–wake cycle with increased number of wakings at night was notable during about 1 month after delivery, compared to the late pregnancy period, and subsequently this number tended to decrease. These results were indicative of the association between the lactation cycle to neonates and the sleep–wake cycle.

CHANGES OF SLEEP OR WAKING HABITS BY AGE AND SEX IN JAPANESE

We analyzed the effects of age and sex on habitual sleep/wake rhythm and Morningness–Eveningness scores of 2,252 subjects (6–89 years) randomly selected in Shimonoseki, Japan. Subjects were divided into 21 age groups with a matching number of men and women in each age group. The most common sleep parameter patterns by age showed a v- or ^-pattern with a turning point in young adulthood or at the period of puberty. During the period between 6 yr. of age to puberty or young adulthood, the bedtimes on weekdays and weekends and the waking times on weekends were delayed, Morningness–Eveningness scores shifted to the evening type, and sleep length on weekdays decreased. After that period, across groups of increasing age, bedtime and waking time on weekdays and weekends became earlier, sleep length on weekdays and sleep latency increased, Morningness–Eveningness scores shifted to morning type, and the number of awakenings increased. The number of daytime naps increased in the 16–19 yr. group, decreased slightly after that age group, but increased again in older groups. The weekday bedtimes of women above 40 yr. of age was significantly later and their sleep lengths significantly shorter than those of men of the same age. Average sleep latency was longer for women than men. The number of awakenings was larger in women above 50 yr. of age than men of the same age group. The turning point of age gained from the two linear regressions on data for subjects that have a minimum sum of squared error, was between 16 and 25 yr. of age. Average phase of sleep/wake rhythm shifted backward and sleep length decreased in groups from age 6 to puberty or young adulthood. After early adolescence, the average phase of the sleep/wake rhythm shifted forward, sleep latency became longer, and daytime napping increased. Number of awakenings increased rapidly for womens groups over 40 yr. of age and for mens groups after 50 yr. of age. Sex differences in our research are in apparent conflict with previous data and are discussed from the perspective of womens social and domestic roles in Japan.

Age and gender difference in habitual sleep–wake rhythm

We analysed the effects of age and gender on the habitual sleep–wake rhythm in 2252 randomly selected subjects living in Shimonoseki, Japan. Subjects were divided into 21 age groups with a matching number of males and females for each. During the period from primary school to adolescence, the bedtime became delayed and sleep length decreased with age. After that period, with increasing age, bedtime became earlier and sleep length increased. The number of awakenings and the length of daytime naps increased markedly with epoch after 50 years and 70 years of age, respectively. Gender differences were considered to be due to the women’s social and domestic customs in Japan.

Effects of Age and Gender on Sleep Habits and Sleep Trouble for Aged People

The healthy 455 subjects above 60 years of age were questioned on their sleep habit inventory and the morningness-eveningness questionnaire. We analyzed the effects of age and sex on sleep habits and sleep-related trouble. Bedtimes on weekdays and weekends became earlier with aging, and women went to bed significantly later than men did. The length of sleep on weekdays slightly increased with aging, and it was longer for men than for women. The number of urinations and awakenings during nocturnal sleep and the amount of daytime napping increased with aging. The score on morningness-eveningness shifted toward the morning type with aging. In comparison with men, women had significantly longer sleep latency; and a higher percentage of subjects who reported that they sleep for only a short time, have sleep trouble, have received medical treatment for their sleep trouble, and take sleep medication. From these results, we deduced that the phase of sleep shifted forward in subjects above 60 years of age, and they showed frequent interruptions during nocturnal sleep and long daytime napping. We discussed the factor of gender difference in sleep in relation to social and cultural factors, particularly the household activities of women.

Changes in sleep patterns during He-O2 saturation dives

Abstract During simulated hyperbaric saturation diving experiments of He‐02 mixture at the depths of 150, 180 and 230 m the standard polysomnography of four divers, as well as their subjective feelings of fatigue, were recorded for 268 nights. In all three diving conditions, during the bottom period and the decompression period, wakes after sleep onset and Stage 1 sleep increased while Stage 4 sleep decreased. In deeper diving conditions stage 4 sleep tended to decrease and subjective feelings of fatigue increased. When the results are considered it can be assumed that the deeper the diving depths, the increased sleep disturbances and fatigue. However, it is believed that a fundamental sleep pattern will be maintained.