By Rachel Mahan, published on January 1, 2009 - last reviewed on November 19, 2013
Name: Jeffrey Yu
Profession: Ob/Gyn Medical Resident
Working at St. Luke's-Roosevelt Hospital in New York City, Jeffrey Yu often has to put in 26-hour shifts on weekends. "There's really no way to catch up on the sleep," he says, because he has to work again at 6 a.m. on Monday. His coping strategy: Five to six cups of coffee during the long shifts and maybe a few minutes of shut-eye on the beds the hospital provides. It's hard on his body, he says. Even after eight or nine hours of rest, he's still groggy.
The circadian cycle is so important to functioning that your memory may depend on it. Animals whose circadian rhythms were eliminated by changing periods of light and dark had trouble remembering objects they had encountered only 20 minutes before. When they were treated with a compound that blocks the neurotransmitter GABA, learning returned, independent of sleep. Dampening GABA may open a whole new route to reversing memory loss with age.
While we may not even be aware of our moods, our behavior reflects the fact that our emotions have their own intrinsic cycle throughout the day. Actions that indicate positive emotions, such as laughing and socializing, follow a wave-like pattern that peaks about 10 to 12 hours after waking up.
An internal food clock can override the primary body clock, which is tuned to periods of light and dark. This is important for survival because sometimes food is available only while animals are asleep. Researchers suggest you may be able to snap quickly into a new time zone and avoid jet lag by fasting for 16 hours before an arrival feast.
Rooting for your favorite team? How well they do may depend on their circadian advantage. Major league baseball teams that are more acclimated to a time zone win more often. It takes about a day to get used to a new time zone for every zone crossed, research says.
Disrupted sleep schedules make people feel groggy and irritable. More serious side effects could include cardiovascular and kidney disease, researchers found while studying hamsters. Shift workers should try to maintain schedules for at least a month at a time, rather than more frequently switching between night and day, to give their bodies time for adjustment.