Nationwide cross-sectional population-based study on the prevalences of asthma and asthma symptoms among Japanese adults.

BACKGROUND: Asthma is a common respiratory disease worldwide. However, few reports are available on the prevalences of asthma and asthma symptoms among Asian subjects. METHODS: To determine the prevalences of asthma and asthma symptoms among Japanese subjects, we performed a nationwide cross-sectional, population-based study on Japanese adults aged 20-79 years. Ten areas spread throughout the country were randomly selected. Door-to-door or postal surveys were performed using a translated version of the European Community Respiratory Health Survey questionnaire. RESULTS: The survey was completed by 23,483 participants. The overall response rate was 70.6%. The prevalences of wheeze and current asthma among all participants aged 20-79 years were 10.1% (95% CI: 9.7-10.5%) and 4.2% (95% CI: 4.0-4.5%), respectively. The prevalences among young adults aged 20-44 years were 9.3% (95% CI: 8.7-9.9%) and 5.3% (95% CI: 4.8-5.8%), respectively. The prevalence of current asthma was highest in females aged 30-39 years in comparison with the other gender and age groups. CONCLUSIONS: This nationwide study determined the prevalences of asthma and asthma symptoms among Japanese adults. The results provide fundamental information on the respiratory health of Japanese adults.

Five-hour sleep restriction for 7 days increases subjective sleepiness.

We investigated the effects of a 5-h sleep restriction for 7 d on subjective sleepiness in an ambulatory condition by comparing them with baseline conditions consisting of an 8-h sleep for 7 consecutive days. Subjects were 13 healthy male students (mean age 21.1 yr). Each subject was required to get 8 h of sleep (baseline, from 2300 to 0700) for 7 d, and 5 h of sleep (sleep restriction, from 0100 to 0600) for 7 d in an ambulatory condition. The order of the two sleep schedules was randomly assigned. Subjective sleepiness was assessed by a Visual Analog Scale (VAS) every 3 h at 0900, 1200, 1500, 1800, and 2100 for 7 successive days during each sleep schedule. The VAS score during sleep restriction gradually increased up to the 5th day and then reached a plateau. The patterns of time-course changes in the VAS score were similar to those at baseline. The VAS scores showed a peak at 0900, taking a dip at 1200, and then gradually increasing toward 2100. The mean VAS score of the last three days of the 5-h sleep restriction was significantly higher than that at baseline (p<0.001). A 5-h sleep restriction for 7 d in an ambulatory condition increased subjective sleepiness up to the 5th day and then reached a plateau. The patterns of the time-course changes in sleepiness of 5-h sleep restriction per day did not differ from that at baseline.

Acute effects of cigarette smoking on the heart rate variability of taxi drivers during work.

OBJECTIVES: This study attempted to clarify the acute effects of cigarette smoking on autonomic nervous function among taxi drivers under ordinary work conditions. METHODS: Holter electrocardiographic recordings from 20 healthy middle-aged taxi drivers were analyzed for the time from 0800 in the morning to 0159 at night. The amplitudes (milliseconds) of the high-frequency (HF) component and the ratio of the low-frequency component to HF (LF/HF) were calculated as changes in the R-R interval, and time-course changes were investigated by a complex demodulation method. The exact starting time of smoking was identified with the use of a specially designed cigarette lighter. The mean LF/HF and HF for 5 minutes immediately prior to smoking were calculated as the baseline, and the means for every 5 minutes up to 15 minutes were calculated. The average values of these parameters for all of the cigarette smoking within the same time span of 0800-1659 and 1700-0159 were also determined. RESULTS: The LF/HF significantly increased (P<0.05) within 5 minutes from the baseline immediately after smoking. This significant change in LF/HF was observed only at night. Although the interactive effect of the time of day on time course changes was not significant for the LF/HF or HF, the reactivity to increase LF/HF and decrease HF was more prominent at night. CONCLUSIONS: Cigarette smoking significantly increased LF/HF within 5 minutes during ordinary taxi driving. Nighttime smoking seemed to have a more potent acute effect on the cardiac modulation of taxi drivers than in the daytime. The sympathomimetic and parasympatho-withdrawal response of smoking may play an additional role in increasing cardiac risk among taxi drivers.

Effects of changing shift schedules from a full-day to a half-day shift before a night shift on physical activities and sleep patterns of single nurses and married nurses with children.

To clarify the effects of changing shift schedules from a full-day to a half-day before a night shift, 12 single nurses and 18 married nurses with children that engaged in night shift work in a Japanese hospital were investigated. Subjects worked 2 different shift patterns consisting of a night shift after a half-day shift (HF-N) and a night shift after a day shift (D-N). Physical activity levels were recorded with a physical activity volume meter to measure sleep/wake time more precisely without restricting subjects' activities. The duration of sleep before a night shift of married nurses was significantly shorter than that of single nurses for both shift schedules. Changing shift from the D-N to the HF-N increased the duration of sleep before a night shift for both groups, and made wake-up time earlier for single nurses only. Repeated ANCOVA of the series of physical activities showed significant differences with shift (p < 0.01) and marriage (p < 0.01) for variances, and age (p < 0.05) for a covariance. The paired t-test to compare the effects of changing shift patterns in each subject group and ANCOVA for examining the hourly activity differences between single and married nurses showed that the effects of a change in shift schedules seemed to have less effect on married nurses than single nurses. These differences might due to the differences of their family/home responsibilities.