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motion sensor technology

Questionnaire survey was conducted using valid and reliable self-administered questionnaires described previously [15]. Briefly, we used the Morning Evening Questionnaire (MEQ) [23], which is a self-assessment questionnaire developed primarily for screening candidates for sleep-related experiments to evaluate morningness and eveningness in individuals. A high MEQ score represents morning type.

The Pittsburg Sleep Quality Index (PSQI) [24] is a self-administered questionnaire designed to evaluate sleep quality and consists of 18 items that in turn are comprised of 7 components, with each weighted equally on a 0–3 scale to be summed to yield the global PSQI score ranging from 0 to 21, where the higher the scores, the worse the sleep quality.

The participating patients also completed the BDI (Beck Depression inventory)-II, which is a 21-item questionnaire [25]. A high BDI score represents depressive state.

Dietary habits during the preceding month were assessed with the validated, Brief, self-administered Diet History Questionnaire (BDHQ). The BDHQ is a 4-page structured questionnaire that asks about consumption frequency of selected foods to estimate the dietary intake of 56 food and beverage items with specified serving size described in terms of consumption in general Japanese populations[26].

Physical activity level was assessed with the International Physical Activity Questionnaire (IPAQ) that comprises four simple questions on physical activity [27]. The IPAQ results are expressed as metabolic equivalent scores (METs·hour-week−1).

Workers were defined as full-time employees or shift workers by a question in the questionnaire as described previously [15]. The subjects were also divided into non-smokers, former smokers or current smokers, as described previously[15]. Estimation of the total number of cigarettes was calculated by cigarettes smoked per day times smoking duration (years).