Shuichiro Shirakawa

Seasonal variation of mood and behaviour in a healthy middle‐aged population in Japan

A population survey of seasonality in six representative cities in Japan was conducted using the Japanese version of the Seasonal Pattern Assessment Questionnaire (SPAQ). The questionnaires were given to 951 parents (male: female ratio 1 : 1 age range 34‐59 years) of high‐school students. Significant regional differences in seasonal variations of mood, length of sleep, and weight were observed; the proportion of individuals reporting high seasonality in the two northern cities was significantly higher than that in the other areas. These results provide evidence for a northern predominance in the prevalence of seasonal affective disorder in Japan.

The psychological aspects of patients with delayed sleep phase syndrome (DSPS)

OBJECTIVE The current study attempts to define the psychological features of patients with delayed sleep-phase syndrome (DSPS). METHOD We administered the Yatabe-Guilford test (Y-G test), Minnesota Multiphasic Personality Inventory (MMPI), Picture-Frustration study (P-F study) and Rorschach test to two groups, one of patients with DSPS (case group) and the other of people without psychiatric symptoms or insomnia (control group). RESULTS Overall, the results of the tests indicate that patients with DSPS showed emotional features such as nervousness, depression and lack of control of emotional expression. Specific personality traits included introspection, defensiveness, aspiration for intellectual attainment with compulsivity, overly abstract thinking, unawareness of impulsivity to immediate gratification, perseverance and reduced cognitive ability. In addition, the patients with DSPS showed psychopathological features similar to those of neurosis, hypochondriasis, depression, conversion hysteria and psychopathic deviate. CONCLUSIONS There seems to exist a definite psychological profile for patients with DSPS. (1) an excessive defense mechanism that increases nervousness and develops neurosis; (2) a high level of intellectual aspiration with compulsivity that makes the patients feel self-defeated, powerless and disappointed; (3) a tendency to egocentric emotion, inhibition and perseverance. These characteristics may worsen social withdrawal, causing a loss of social cues in synchronizing their circadian rhythm. Thus, the phase shift becomes more difficult and a vicious circle is constituted.

Demography of sleep disturbances associated with circadian rhythm disorders in Japan

To clarify the demography of delayed sleep phase syndrome (DSPS), non‐24‐h sleep–wake syndrome, and irregular sleep–wake pattern in Japan, a cross‐sectional nationwide epidemiological survey was conducted. 1525 adults (age: 15–59 years) were randomly sampled from telephone directories, and they received screening questions over the phone. Persons who were suspected of having the disorders were requested to fill out the second questionnaire, and asked to keep a sleep log for 4 weeks. Diagnoses were made according to the International Classification of Sleep Disorders criteria. As a result, the prevalence of DSPS was estimated to be 0.13%.

Restless legs syndrome in hemodialysis patients: health-related quality of life and laboratory data analysis.

AIMS To compare clinical data, sleep quality and health-related quality of life (HRQOL) with and without RLS in HD patients. MATERIALS AND METHODS The international RLS study group diagnosis questionnaire was completed by 228 HD patients. The Pittsburg Sleep Quality Index (PSQI) for the evaluation of sleep quality and the Kidney Disease Quality of Life (KDQOL-SF) for the analysis of HRQOL were also used. RESULTS 53 (23%) patients were diagnosed as RLS. Age and age at the initiation of HD were significantly younger in the RLS group. Serum calcium concentration (Ca) was significantly higher in the RLS group. Sleep quality evaluated by PSQI was significantly lower in the RLS group. In SF-36 domains of KDQOL-SF, bodily pain, general health perceptions, vitality, role functioning emotional, mental health and mental component score were significantly lower in the RLS group. In kidney targeted scales of KDQOL-SF, symptoms/problems, burden of kidney disease, cognitive function, quality of social interaction, sleep and patient satisfaction were significantly lower in the RLS group. CONCLUSION High Ca was possibly connected to the pathophysiology of RLS which impaired sleep quality as well as HRQOL including mental health and many kidney disease related scales.

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.

Difference in the characteristics of subjective and objective sleepiness between narcolepsy and essential hypersomnia

Abstract  The present study was conducted to investigate the difference in the characteristics of daytime sleepiness between narcolepsy and essential hypersomnia and to identify the relationship between the Epworth Sleepiness Scale (ESS) and the Multiple Sleep Latency Test (MSLT) in patients with these two disorders. Subjects consisted of 34 patients with essential hypersomnia (32.4 ± 11.0 years old), 52 patients with narcolepsy (29.0 ± 13.8 years old), and 45 control subjects (33.3 ± 6.6 years old). The subjects completed the ESS and underwent MSLT following a regular sleep‐wake schedule for over 2 weeks. The ESS scores were pathologically high and mean sleep latency on MSLT was short, not only in narcolepsy but also in essential hypersomnia. With respect to sleep latencies on each MSLT session, both essential hypersomnia and control subjects had the smallest value at 14:00, while narcolepsy lacked any statistical change at this time period. The correlation between ESS and mean sleep latency on MSLT was higher in essential hypersomnia than in narcolepsy, and the correlation was strongest for the session performed at 14:00. Based on the ESS and MSLT results, the severity of excessive daytime sleepiness was significantly milder in essential hypersomnia compared with that in narcolepsy. The results also indicate that diurnal variation of sleepiness was maintained, and the correlation between subjective and objective sleepiness was relatively maintained in essential hypersomnia compared to narcolepsy. It is suggested that the mild disease severity of essential hypersomnia contributed to the formation of these characteristics.

Sleep health and lifestyle of elderly people in Ogimi, a village of longevity.

Abstract The study was conducted in the Prefecture of Longevity, Okinawa, on the elderly living in the village of Ogimi. It was revealed that those in the good sleep health group took short naps, a significantly fewer number fell into dozes, and a significantly greater number exercised regularly or walked. A significantly greater number of this group maintained regular eating habits over a 10‐year span, and consumed more seaweed and fish. Participation in senior citizens’ clubs was higher, reflecting high emotional adaptability. The study’s results indicates a relationship between lifestyle and sleep health among the elderly, and suggest that deterioration of sleep health is related to physical and mental health.

Functional significance of delay-period activity of primate prefrontal neurons in relation to spatial working memory and reward/omission-of-reward expectancy

The lateral prefrontal cortex (LPFC) is important in cognitive control. During the delay period of a working memory (WM) task, primate LPFC neurons show sustained activity that is related to retaining task-relevant cognitive information in WM. However, it has not yet been determined whether LPFC delay neurons are concerned exclusively with the cognitive control of WM task performance. Recent studies have indicated that LPFC neurons also show reward and/or omission-of-reward expectancy-related delay activity, while the functional relationship between WM-related and reward/omission-of-reward expectancy-related delay activity remains unclear. To clarify the functional significance of LPFC delay-period activity for WM task performance, and particularly the functional relationship between these two types of activity, we examined individual delay neurons in the primate LPFC during spatial WM (delayed response) and non-WM (reward–no-reward delayed reaction) tasks. We found significant interactions between these two types of delay activity. The majority of the reward expectancy-related neurons and the minority of the omission-of-reward expectancy-related neurons were involved in spatial WM processes. Spatial WM-related neurons were more likely to be involved in reward expectancy than in omission-of-reward expectancy. In addition, LPFC delay neurons observed during the delayed response task were not concerned exclusively with the cognitive control of task performance; some were related to reward/omission-of-reward expectancy but not to WM, and many showed more memory-related activity for preferred rewards than for less-desirable rewards. Since employing a more preferred reward induced better task performance in the monkeys, as well as enhanced WM-related neuronal activity in the LPFC, the principal function of the LPFC appears to be the integration of cognitive and motivational operations in guiding the organism to obtain a reward more effectively.