The Null Device

An article on how to reprogram your body clock, changing from being a night- to a morning-person or vice versa, for career purposes, romantic compatibility, or just to join a different time-zone tribe:

The body tells time with a master clock in the brain, a pinhead-sized cluster of neurons in the hypothalamus that takes cues from optic nerves that signal sunlight. By sticking people in isolation chambers, scientists discovered that most people's internal clocks run a bit longer about a half-hour on average than the sun's 24-hour cycle. That's why, for most people, it's easier to stay up later and compensate by sleeping in than to force yourself to sleep early and wake early, explains Dr. Eliza Sutton, an acting assistant professor of medicine at the University of Washington. Morning larks are those rarer birds whose body clock is shorter than 24 hours, so they wake up raring to go.

If you're a night owl with sunrise envy, sleep doctors say you can reset your body clock by following these steps:

• Find out how much sleep you really need
• As soon as you wake up, get sunlight exposure for at least 15 to 30 minutes.
• Go to bed earlier (or later) each night
• Stick to your schedule

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