No Correlation Found Between Exercise, Total Sleep Time

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June 11, 2009

The amount of energy you expend during the day may have nothing to do with the amount of sleep you get, according to a study presented at SLEEP 2009. Researchers at Walter Reed Army Medical Center followed 14 subjects wearing armbands designed to measure body temperature, ambient temperature, position sense and motion. The armbands also were programmed to monitor sleep efficiency and sleep time. Researchers discovered that subjects experiencing increased activity during the day had a lower total sleep time each night. On the other hand, they also found that nights with a lower total sleep time were followed by increased activities the next day.

Dr. Arn Eliasson, the study's lead author, told the Times of India , "The longest sleep and best sleep efficiency occurred after days with low non-exercise exertion. Similarly, we expected that better-rested subjects would be more inclined to get exercise or have busier days; however, better-rested subjects got less exercise and had less calorie expenditure." Researchers concluded that the findings could be explained by factors that went unmeasured, such as metabolic profiles, stress and changes in circadian rhythm. Though research shows that exercise is certainly good for one’s body and health, properly timing exercise is necessary to maximize the beneficial effects. For example, a good workout can make you more alert, speed up your metabolism and energize you for the day ahead, but exercise right before bedtime can lead to a poor night’s sleep.