Those tired of pilates and kickboxing may take comfort in a new weight-loss regimen that suggests a welcome alternative: Climb into bed.

A report last month in the International Journal of Obesity found that sleep deprivation is a large contributor to expanding waistlines, and that stocking up on rest could help men and women trying to shed excess pounds. With this treatment, exhausted New Yorkers should have no problem diving into their resolution-inspired diets after a late night on New Year’s Eve.

The link between slumber and slimming down is the idea behind Dr. Jonathan Waitman’s use of “sleep hygiene” to treat his patients at the Comprehensive Weight Control Program at NewYork-Presbyterian Hospital’s Weill Cornell campus on the Upper East Side. His regimen targets where and how a person goes to sleep. For helpless night owls, Dr. Waitman recommends moving the television out of the bedroom, decreasing intake of alcohol and caffeine, and turning off the computer at a reasonable hour.

In the city that never sleeps, adjusting these behaviors could be quite a problem. “New York encourages people to stay up later with so many things running around the clock,” a nutritionist, Cherie Calbom, said. “I’ve heard people say ‘I get by on five to six hours’ like it’s badge of honor.”

In her book,”Sleep Away the Pounds,” to be published next month by Warner Books, Ms. Calbom puts rest on par with diet and exercise. She said that sleeping is “the missing link” in many weight-loss programs.

“Things like Weight Watchers just talk about food and sometimes exercise, and ignore other causes. If every one of those dietary programs included something about sleep, they would see even better results,” she said.

The chief nutritionist at Jenny Craig, Lisa Talamini, said there is something to the idea: “Many individuals overlook rest and think strictly in terms of calories in and calories out. There is a mind component to weight management that’s critical.”

While the introductory questionnaire at Jenny Craig does not inquire about sleep, Ms. Talamini said the screening process identifies certain personalities, such as workaholics, that tend to place other responsibilities ahead of relaxation.

After a late shift or an early meeting, the quest for a quick jolt may lead many dieters astray. “You’ll feel like you need extra energy and that having a snack high in carbohydrates may give you a short burst,” Dr. Waitman said. “But 2-3 hours later, you’ll feel worse than before and might have another. It creates a vicious cycle.”

The report in the November issue of International Journal of Obesity said that lack of sleep affects the hormones that control appetite. A binge after a long night may be the result of increased levels of ghrelin, which causes hunger, and decreased levels of leptin, which causes satiety, the report said. “Ghrelin causes those munchies for carbs, particularly bad carbs like cookies, candy, and high-fat junk like chips and pizzas,” Ms. Calbom said.

Some doctors, however, are skeptical of these reports. Joseph Vasselli, a research associate at the Obesity Research Center at St. Luke’s-Roosevelt hospital, said that there is insufficient evidence and “too much variability” to determine if lack of sleep alters hormones and causes weight gain.

One of these inconsistencies is the order of weight gain and sleep impairment. It is difficult to determine which precedes the other since the physical condition of being overweight tends to cause sleeping troubles of its own.

Sleep apnea, for example, is a common disorder among the obese that causes obstructions in airways that either reduce breathing or stop it completely. When the disruption occurs, most people wake up. “There’s no question that once you become significantly obese, it becomes harder to sleep,” said Mr. Vasselli, who has a Ph.D. in psychology. “So no one really knows whether lack of sleep in beginning triggers obesity.”

Dr. Waitman of the Comprehensive Weight Control Program said it is important to distinguish sleep disorders from sleep deprivation. While apnea is a physical condition that stems from excess weight, there are occupational and lifestyle influences that disrupt the sleep and diet for people of all sizes. Recent studies, he said, tend to focus on those who gain weight as they work graveyard shifts or surf the net into the early morning. When excluding a disorder like apnea, the Journal of Obesity said that obese subjects still reported sleeping poorly.

A National Sleep Foundation poll showed that the average American sleeps less than seven hours each night. According to the National Health and Nutrition Examination Survey, those who fall into this group tend to have a higher body mass index and are more likely to be obese than those who sleep more.

There is also the indisputable fact that, save a few hungry sleepwalkers, a night of slumber provides a break from snacking.

“I had a friend who said that my book worked,” Ms. Calbom said. “She told me, ‘I finally had to take a nap to stop eating.'”