When you catch a cold, curling up in bed to sleep is the only activity you can manage. Sleeping in response to stress isn't a uniquely human behavior: many animals have the same reaction. While the circadian sleep that follows the pattern of the clock has been studied extensively, sleep that's triggered by stress was not understood. Researchers now report stress-induced sleep in the nematode worm Caenorhabditis elegans using ultraviolet C radiation to induce stress. They found that after exposure to UV C radiation, the worms initially wriggled more, but then their movements slowed. Sleeping after stressful events helps the organism funnel more resources into cellular repair. Still, the restorative properties of sleep -- stress-induced remain to be fully understood.
