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A 42-year-old member asked:

For what reasons might the sleepy feeling go away after you stay awake for a long time?

1 doctor answer1 doctor weighed in
Dr. Michael Summers
Sleep Medicine 23 years experience
Circadian Rhythm : Your circadian rhythm has peaks and valleys. Often times the valley (drives you to sleepiness) occurs in the mid afternoon (on conventional sleep-wake schedules). If you "push" through it, you get a second wind in the late afternoon to early evening hours. This is your circadian rhythm coming out of the valley and in to a peak to drive wakefulness.

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Last updated Sep 4, 2013

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