When I feel tired, I can't do much of anything right. I drop things. I say stupid stuff. And I eat with abandon, unable to resist most temptations. • So I made getting more sleep a key component of my "Me Minus 10" campaign to lose 10 pounds before I turn 50. It just seemed obvious that being well rested would help me control my diet. And I did something a journalist never should: I assumed there was science to back me up. • Turns out that science has not yet connected the dots between how much we sleep and how much we weigh.
After searching in vain for convincing studies to support my hunch, I turned to the pros.
"There haven't been that many studies done on that particular topic," said Clete Kushida, president of the American Academy of Sleep Medicine.
Kushida's office sent me a handful of studies, including a 2008 analysis of the existing research on the subject of sleep and obesity. They all revealed a relationship between restricted sleep and obesity, but not one that was cause and effect. The studies noted that further research is needed.
What do we know? Scientists have an idea for how lack of sleep might contribute to obesity. In two studies, lack of sleep was found to influence two hormones that help control hunger. Leptin, made by fat tissue, tells your brain when it's time to stop eating, while ghrelin, which is made in the stomach, signals that you ought to eat more. Both studies — one involving 11 subjects, the other more than a thousand — found that restricted sleep led to suppression of leptin and increased ghrelin activity, two states that could make you want to eat more.
At least one doctor is willing to take the leap and recommend that people who want to lose weight should get a handle on their sleep. Michael Aziz, author of The Perfect 10 Diet (Sourcebooks, 2010), writes, "Getting enough sleep is the cheapest and simplest advice I can give for losing weight."
Aziz is a doctor of internal medicine and founder and director of New York City's Midtown Integrative Medicine, which focuses on traditional, alternative and complementary medicine.
His approach involves choosing foods, behaviors and activities that promote healthful balances of 10 hormones he considers key to weight management. He agrees that ghrelin and leptin are major players in determining how much we weigh. But so, he says, are growth hormone, insulin, cortisol and melatonin. And the activity of each is influenced by how much we sleep.
With those mechanics in mind, Aziz offers some specific advice about how, and how much, to sleep:
• "Go to sleep and wake up at the same time most days." We can perhaps slide a bit on weekends, Aziz says, but usually we should aim to be in bed at — are you ready? — 9:30 or 10 on weeknights.
• Eat your last meal one to two hours before going to bed.
• Avoid what are commonly called simple carbohydrates and "sugary stuff" at that meal or at bedtime. Such foods will bump up insulin production. "When our insulin is very high, we can't get to sleep," he says. Instead, choose whole-wheat crackers, which can control insulin. Or eat turkey or bananas, both of which contain tryptophan, which is believed to trigger sleepiness. Lettuce, too, has a "long history of helping people get to sleep," Aziz says.
• Avoid caffeinated coffee, tea and soda. And alcohol, which Aziz says "can make us go to sleep, but it's not the deep sleep" that we need to produce growth hormone (which in turn helps regulate insulin).
• Practice good sleep hygiene. That means turning off all electronics, including the TV, and creating as quiet a sleep space as you can. Consider taking a warm bath or doing some gentle stretches — but not heart-pumping exercise — before turning in.
Okay, so just how long are we supposed to stay asleep?
Robert Vorona, a sleep researcher at Eastern Virginia Medical School in Norfolk, says adults should aim for 7 to 7 1/2 hours a night, while teenagers need a whopping 9 to 9 1/4 hours. (Fellow parents, let's do the math. If your teen has to get up at, say, 6:30 to be at school by 7:30, that means bedtime's at 9:15 or 9:30 p.m.)
Vorona says he'd like to delve deeper into the sleep-obesity question. He applied for funding of the research a few years ago, to no avail. "It's a shame," he says. "It's such an intriguing idea. If sleep extension could have a salutary effect on helping people lose weight," he says, we'd have another tool in the fight against obesity.
On the other hand, Vorona says, "The last thing I want readers to think is that Dr. Vorona thinks we're facing this obesity epidemic because we're sleep deprived. I suspect it's part of the picture, along with lack of exercise and dietary indiscretion."