Date Published: January 20, 2004
Publisher: Public Library of Science
Partial Text: How does your brain pass the time while you’re sleeping? If you’ve ever wrestled the demons of insomnia, you know what sleepless nights can do to your mental agility. Sleep cycles in mammals are characterized by two distinct, successive sleep stages: slow wave and rapid eye movement (REM). Both stages of sleep have uniquely associated electrical activity in the brain, which neuroscientists can measure by placing elec-trodes on the brain during sleeping and waking states. What neuroscientists can’t easily measure is the purpose of these two sequential sleep stages.