Reset Your Inner Clock

New insights on the link between exercise and rest

Nov 1, 2001
Outside Magazine

Light sleeper: Sunshine plus exercise equals rest

BEFORE YOU retreat pathetically into your annual winter hibernation, we have some words of caution: It won't be long until you're losing sleep over your lazy new lifestyle. Early results in a $2 million research project by University of California-San Diego sleep guru Shawn Youngstedt show that one hour of daily moderate exercise can have a profound effect on the quality of your slumber by steadying your circadian rhythms, the daily patterns of activity regulated by your internal body clock. More important, you can enhance the benefits if you exercise outside instead of under the soul-sucking flourescent lights of the gym. "If you can get natural light and exercise together," says Youngstedt, "you could increase the amplitude of your rhythm." Thus, to get deeper sleep, get outside.

The individual connections between light, sleep, and exercise are well documented. A 1997 Stanford University study showed that people who do four heart-pumping workouts a week nod off faster and sleep as much as an hour longer than sofa spuds; and several studies conducted in the past decade verify that soaking up bright light during the day helps tune the body's clock by reducing the production of melatonin, a compound that helps induce sleep. Now Youngstedt, an amateur triathlete with a decade of experience studying sleep science, is producing the most comprehensive data yet through his four-year study on the synergistic effects of exercise, sleep, and light on the body's internal clock. After subjecting one group of volunteers to exercise and another to bright light, his investigation found that both groups enjoyed improved sleep patterns. So, the thinking goes, combining them would yield the best rest.
With today's average American getting less than an hour of sunlight each day, outdoor exercise may be the key to good slumber. But doctors aren't yet prescribing bike rides over sleeping pills. "It's still a new concept," admits Youngstedt. "Getting outside is the important thing, but people today are outdoors much less than our ancestors."Sick of counting sheep? Try the tips below.

The Sleep Regulator

THINK OF YOUR body clock as a droning New Age tune. Circadian rhythms are the song's steady drummer, an internal Yanni playing two important beats a day: an initial snare tap in the morning that causes the body's temperature to rise, signaling you to wake up, and a bass thump as night falls, triggering a drop in temperature and the production of melatonin to make you drowsy. Ideally, the beat should remain consistent—so you sleep and wake at the same time each day. But when work, travel, stress, and car alarms change the beat daily, sleep suffers. According to Youngstedt, a regular routine of outdoor exercise will keep your internal Yanni in line: Exposure to sunlight in the afternoon will delay sleepiness in the evening, and the exercise will help cue your body's fatigue at approximately the same time each day.

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