More than 60% of women don’t regularly get the recommended seven to nine hours of sleep per night. As sleep debt mounts, health consequences increase. It may take some work, but you can repay even a chronic, longstanding sleep debt, reports the July 2007 issue of Harvard Women’s Health Watch.

Sleep loss exacts a toll on the mind as well as the body, research has shown. In one study, scientists assigned groups of healthy men and women, ages 21 to 38, to get different amounts of sleep— eight, six, or four hours per night—or no sleep at all for three nights in a row. No one was allowed to sleep during the day. Every two hours during their waking periods, all the participants completed sleepiness questionnaires and took tests for reaction time, memory, and cognitive ability.

Over the course of two weeks, reaction times in the group that slept eight hours a night remained about the same, and their scores on memory and cognitive tasks rose steadily. In contrast, scores for the four- and six-hour sleepers drew closer to those of the sleepless group, whose scores had plummeted.

So how do we counter the effects of chronic sleep loss? Harvard Women’s Health Watch suggests if you’ve missed 10 hours of sleep over one week, make up for it over the weekend and the following week. If you’ve missed sleep for decades, it could take a few weeks to repay the debt. Plan a vacation with a light schedule, and sleep every night until you wake naturally. Once you’ve determined how much sleep you need, factor it into your daily schedule.