Yukari Yamamoto

Intrinsic dreams are not produced without REM sleep mechanisms: evidence through elicitation of sleep onset REM periods

The hypothesis that there is a strict relationship between dreams and a specific rapid eye movement (REM) sleep mechanism is controversial. Many researchers have recently denied this relationship, yet none of their studies have simultaneously controlled both sleep length and depth prior to non‐REM (NREM) and REM sleep awakenings, due to the natural rigid order of the NREM–REM sleep cycle. The failure to control sleep length and depth prior to arousal has confounded interpretations of the REM‐dreams relationship. We have hypothesised that different physiological mechanisms underlie dreaming during REM and NREM sleep, based on recent findings concerning the specificity of REM sleep for cognitive function. Using the Sleep Interruption Technique, we elicited sleep onset REM periods (SOREMP) from 13 normal subjects to collect SOREMP and sleep onset NREM (NREMP) dreams without the confounds described above. Regression analyses showed that SOREMP dream occurrences were significantly related to the amount of REM sleep, while NREMP dream occurrences were related to arousals from NREM sleep. Dream properties evaluated using the Dream Property Scale showed qualitative differences between SOREMP and NREMP dream reports. These results support our hypothesis and we have concluded that although ‘dreaming’ may occur during both REM and NREM periods as previous researchers have suggested, the dreams obtained from these distinct periods differ significantly in their quantitative and qualitative aspects and are likely to be produced by different mechanisms.

Effects of short nap and exercise on elderly people having difficulty in sleeping.

The purpose of the present study was to examine the effects of short nap and exercise on the sleep quality of elderly people who reported difficulty in sleeping. ‘Interventions’ such as short nap after lunch and moderate‐intensity exercise in the evening were carried out for 4 weeks. After the ‘interventions’, wake time after sleep onset significantly decreased and sleep efficiency significantly increased, which showed that sleep quality was improved. The frequency of nodding in the evening significantly decreased. These results demonstrated that the proper awakening maintenance in the evening was effective in improving sleep quality. After the ‘intervention’, mental health was also improved with improving sleep quality.

Short naps and exercise improve sleep quality and mental health in the elderly

Abstract The effects of short naps and exercise on the sleep quality and mental health of elderly people was investigated. ‘Interventions’ by short naps after lunch and exercise of moderate intensity in the evening were carried out for 4 weeks. After the ‘intervention’, awake time after sleep onset decreased significantly and sleep efficiency increased significantly, demonstrating that sleep quality had improved. Also, the frequency of nodding in the evening decreased significantly. These results demonstrate that proper awakening maintenance in the evening was effective in improving sleep quality. After the ‘intervention’, mental health and volition and physical health had also improved with improving sleep quality.

An examination of sleep health, lifestyle and mental health in junior high school students

Abstract The factors that influence sleep health and mental health in junior high school students’ lifestyles was examined. The proportion of students who replied that they feel bad in the morning, and who do not have breakfast was significantly higher in poor sleepers. The proportion of students who regularly take exercise was significantly lower among poor sleepers. Compared with good sleepers, poor sleepers had a higher number of illnesses and their General Health Questionnaire score was worse. The study’s results suggest that sleep health is closely related to both physical and mental health, and that habits such as exercise, and regular sleeping and eating, are important for maintaining and improving students’ sleep health.

Survey of sleep-health and lifestyle of the elderly in Okinawa.

A total of 788 people (aged from 60 to 93 years) living in the Okinawa prefecture, renowned for the long life expectancy of its citizens, were randomly chosen as subjects. A questionnaire based on lifestyle and sleep‐health was distributed. Following this, subjects were chosen in groups of nine from the good sleep‐health group and then from the poor sleep‐health group based on the results of the survey; their physical activities were then recorded using actigraphs for 1 week. This study suggested that lifestyle, such as exercise, walking and short naps, occupies an important position in the maintenance and improvement of sleep‐health. It also verified the reliability of the sleep‐health risk index and the questionnaire.

Core temperature pattern and self-rated lifestyle

Abstract We investigated the relationship between a subjects self‐rated lifestyle and their pattern of nocturnal rectal temperature. Fifty‐five students participated in the study. Among several significant findings, irregularity and eveningness component of lifestyle (irregular and delayed sleep phase) showed a significant negative correlation with temperature at the morning rising time. Examination of the nocturnal temperature pattern revealed that rectal temperature stayed at its lowest level in the early morning hours in the subjects with irregular and eveningness‐like lifestyles.

Is the sleep initiating process affected by psychological factors

The aim of this study was to investigate the effects of psychological factors on sleep initiating process. The Y‐G personality test (Y‐G), Lazarus‐type stress coping inventory (SCI), Zung self‐rating depression scale, General health questionnaire, and Sleep health questionnaire were administered to 418 subjects (mean age = 21.13 ± 8.76 years), and the data were analyzed by multiple regression analysis (stepwise variable reduction method). Self‐rating depression scale; Co‐Em, Pla, Sel scale in SCI; C, N, O, Co scale in Y‐G were significantly included in the final model. The results showed that psychological factors, such as depression, emotion‐focused coping behaviour, prudent planning to solve problems, low self‐control, small changes of feeling, nervousness, subjectiveness, and cooperativeness are associated with difficulty initiating sleep.

Classification of the sleeping pattern of normal adults

A questionnaire concerning their sleep‐related lifestyle and mental health was mailed to people aged in their twenties to fifties living in the Fukushima (North East), Tokyo (Central, Metropolitan) and Okayama (West) areas of Japan. We classified the sleeping pattern of 3642 people (1702 men, 1940 women; mean age 41.3 ± 10.67) by multivariational analyses (factor analysis and cluster analysis). They were classified into six groups and defined as ‘poor sleeper group’ (30.0%), ‘good sleeper group’ (28.3%), ‘long sleeper group’ (8.2%), ‘short sleeper group’ (18.5%), ‘irregular sleeper group’ (11.3%), and ‘Delayed Sleep Phase Syndrome group’ (3.7%) based on their characteristics of the factor pattern.