Ever pulled an all-nighter, then started to feel alert around 7 or 8 a.m.? That was your internal clock jolting you awake just when you wished you could crawl under the covers.
Researchers know that when and how long our bodies want to sleep are separate but interrelated behaviors. One system, the internal clock, controls the daily, or circadian, rhythm of when we have the urge to go to bed and wake up. The second, the so-called sleep-wake system, determines how much rest our bodies need.
At least one study already has shown that the internal clock also influences the duration of sleep, but scientists have been in the dark about how this influence plays out inside cells.
Reporting in the November Journal of Neuroscience, Fred W. Turek of Northwestern University in Evanston, Ill., and his colleagues offer what they say is the first evidence of a molecular link between the internal clock and the sleep-wake system.