Great question. There have certainly been a lot of studies done to evaluate the association between sleep and weight. And while there isn't a clear-cut answer to your question, there's definitely a link between the two that's worth considering. Check it out...
Science suggests that the less you sleep, the hungrier you'll feel. There are two "hunger hormones" -- ghrelin, which increases your appetite; and leptin, which suppresses your appetite. When you don't get enough sleep, your body produces more ghrelin... which means you’re gonna feel hungrier. Whoa!
Research confirms the hunger hormones have a real-life effect. One study found that when participants were sleep deprived, they bought more food at the supermarket than they did after a full night of sleep. Another study revealed that if you don't sleep enough, your body could actually burn fewer calories the next day. A third study found a link between decreased sleep and increased consumption of snacks and overall calories. And in one of the largest studies on the subject, researchers evaluated the sleep habits of more than 68,000 women over a 16-year period; the shorter-duration sleepers gained more weight than the others. Pretty convincing stuff!
From a non-scientific standpoint, I definitely feel that sleeping well can be helpful for weight loss. Think about it: After a night of tossing and turning, we're more likely to make questionable food choices -- our minds aren't as sharp when we're sleep deprived, and it's common to turn to food (especially sugar and caffeine) for energy. Beyond that, when we're well rested, we have more energy to exercise. And let's not forget the obvious: The earlier you go to bed, the less late-night snacking you'll be able to do! (Pssst... Click here for tips on resisting nighttime desserts.)
In short? Sleeping poorly for a few nights isn't going to immediately make you gain weight, and sleeping well won't automatically make you lose weight. But a good sleep schedule can certainly help your weight-loss or weight-management goals. It definitely won't hurt!
My best advice if you struggle to get enough sleep? Try to wind down about half an hour before bedtime. Put away your smartphone, don't play any loud music, etc. Limit your caffeine intake late in the day, since even an afternoon coffee can keep us up at night. It's also a good idea to have dinner or your final snack of the day pretty well in advance of the time you want your head to hit the pillow -- a full stomach totally keeps me awake. If you do get a poor night's sleep, don't panic. Just remember that while eating sugar is tempting, it won't help you stay awake and alert in the long run. In fact, this study found that drinking high-sugar, low-caffeine beverages doesn't make you feel less sleepy. If you're craving caffeine, go for black coffee or green tea with a splash of fat-free milk and a bit of no-calorie sweetener -- the caffeine will give you an energy boost without extra calories. Lean protein is also a good choice; it'll give you some energy and leave you feeling full (thus less likely to turn to excess food). Finally, push yourself to get in some physical activity. It might sound counterintuitive, but exercise can actually make you feel less tired.