OBJECTIVES: To examine variations in sleep and wakefulness associated with international travel. METHODS: Ten academics in Japan were studied while traveling abroad to participate in conferences. Wrist activity and a daily log were recorded continuously for 1 week before, during, and for 1 week after travel. Destinations included the USA and Canada to the east (8 to 11-h time difference; mean stay of 6.8 days) and Europe to the west (7 to 8-h time difference; mean stay of 6.0 days). RESULTS: For eastward-traveling subjects, the total sleep time was shorter and the mean activity during sleep was greater at the destinations than before departure. These sleep disruptions persisted until the 2nd day after the subjects had returned home. The sleep patterns then recovered in a zigzag manner. No significant disruptions in the main sleep were found in westward travelers, although these subjects took a longer nap immediately after their return. The beginning and end of sleep occurred earlier until the 2nd day after the subjects had returned from eastward trips, but occurred later until the 5th day after return from westward trips. CONCLUSIONS: In academics, short-term international travel causes sleep disturbances both during and at home after eastward travel and a delay in the sleep timing at home after westward travel. Although the subjects in this study might be atypical of business travelers, the current data suggest that strategies are needed to facilitate recovery from disturbed sleep-wake patterns at home after travel, i.e., redesign of post-travel work schedules.
OBJECTIVES: To examine variations in sleep and wakefulness associated with international travel. METHODS: Ten academics in Japan were studied while traveling abroad to participate in conferences. Wrist activity and a daily log were recorded continuously for 1 week before, during, and for 1 week after travel. Destinations included the USA and Canada to the east (8 to 11-h time difference; mean stay of 6.8 days) and Europe to the west (7 to 8-h time difference; mean stay of 6.0 days). RESULTS: For eastward-traveling subjects, the total sleep time was shorter and the mean activity during sleep was greater at the destinations than before departure. These sleep disruptions persisted until the 2nd day after the subjects had returned home. The sleep patterns then recovered in a zigzag manner. No significant disruptions in the main sleep were found in westward travelers, although these subjects took a longer nap immediately after their return. The beginning and end of sleep occurred earlier until the 2nd day after the subjects had returned from eastward trips, but occurred later until the 5th day after return from westward trips. CONCLUSIONS: In academics, short-term international travel causes sleep disturbances both during and at home after eastward travel and a delay in the sleep timing at home after westward travel. Although the subjects in this study might be atypical of business travelers, the current data suggest that strategies are needed to facilitate recovery from disturbed sleep-wake patterns at home after travel, i.e., redesign of post-travel work schedules.