SSS 2009-03-06（在线收听）

This is Scientific American's 60-Second Science. I'm Christie Nicholson. This will just take a minute.

Ticking clock indeed.  Already it’s time to turn clocks forward one hour this Sunday morning, March 8th.

Two years ago Congress ordered Daylight Saving Time to launch three weeks early, in an effort to save energy. More evening light may mean less electricity used.

But it also means more blues for those prone to winter depression. The change actually sets us back to mid-January in terms of morning light, according to Michael Terman, a biological rhythms expert at Columbia University.

Light is what preps us for waking, alerting the brain to increase body temperature and cortisol, and decrease melatonin. When we’re forced to wake in darkness, we feel like it’s the middle of the night, and from our body’s perspective it is, and we’re tired.

Terman’s recent research shows there is more depression on the western edges of time zones in the U.S., where the sun rises later.

Simplest way to combat this, says David Avery, professor of psychiatry at the University of Washington, is to use a dawn simulator, a device that creates gradual light, or program your bedside lamp to turn on about 20 minutes before you wake up.

Thanks for the minute for Scientific American's 60-Second Science. I'm Christie Nicholson.