Saturday, February 04, 2006

Snooze, You Win

(From FotF's Pastor's Weekly Briefing)

According to new studies, nothing tunes up mind and body like a good power nap. But there's an art to catching the right kind of z's.

Napping in general benefits heart functioning, hormonal maintenance and cell repair, says Dr. Sara Mednick, a scientist at the Salk Institute for Biological Studies who is at the forefront of napping research. A power nap, says Mednick, simply maximizes these benefits by getting the sleeper into and out of rejuvenative sleep as fast as possible.

Here's how the power nap works. Sleep comes in five stages that recur cyclically throughout a typical night, and a power nap seeks to include just the first two of them. The initial stage features the sinking into sleep as electrical brain activity, eye and jaw-muscle movement, and respiration slow. The second is a light but restful sleep in which the body gets ready — lowering temperature, relaxing muscles further — for the entry into the deep and dreamless "slow-wave sleep" that occurs in stages three and four. Stage five, of course, is REM, when the eyes twitch and dreaming becomes intense.

The five stages repeat every 90 to 120 minutes. Stage one can last up to 10 minutes, stage two until the 20th minute. Experts believe that the optimal power nap should roughly coincide with the first 20 minutes in order to give you full access to stage two's restorative benefits. In addition to generally improving alertness and stamina, stage two is marked by certain electrical signals in the nervous system that seem to solidify the connection between neurons involved in muscle memory.

Mednick's most recent research also shows that power naps can lift productivity and mood, lower stress, and improve memory and learning. In fact, Mednick has found through MRIs of nappers that brain activity stays high throughout the day with a nap; without one, it declines as the day wears on.

There is, however, a pitfall in all of this. You have to carefully time the duration of your nap in order to avoid waking in slow-wave sleep. This can produce what's known as sleep inertia, when limbs feel like concrete, the eyes can't focus, the speech is slurred and the mind is sluggish. You must keep the nap to 20 minutes or slightly less — and, if you need the extra sleep, wait until the 50-minute mark. This will safely keep you on the power side of your nap.

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