Good sleep helps control weight. Poor sleep leads to weight gain and vice versa. These are general statements, of course, and individual experience may vary, but if you are trying to diet and lose weight or you are trying to improve your sleep, it pays to keep these interactions in mind.
It is hard to get to sleep when you are hungry. Many diets prescribe lighter meals in the morning and mid-day with a larger meal in the evening, perhaps at least partly to reduce the risk of hunger at bedtime. The blood serum levels of hormones ghrelin and lectin are tied up with sleeping and waking.
Obesity rates have risen in the US and worldwide in recent years as sleep times have (possibly) declined. It is important to not read too much into this. It is interesting, though, and there may be a little bit of cause-and-effect going on.
Lack of sleep increases risk for metabolic syndrome. Fragmented sleep disrupts glucose levels and can lead to related disorders. Metabolic syndrome is marked by two or more of the following: hypertension, insulin resistance, dyslipidaemia, and obesity, especially with excess weight in the belly. It is very common in middle-aged Americans.
Here are some scary numbers that should convince you of the value of sleep. A study found 7-8 hours of sleep per night - 22% have metabolic syndrome 6-7 hours per night – 48% have metabolic syndrome Less than 6 hours per night – 83% have metabolic syndrome Further long sleepers also have an increased risk of the syndrome. The 7-8 hours seems a sweet spot.
An article published in the scientific Journal Sleep a few years ago went so far as to claim sleep problems could predict the onset of metabolic syndrome. Both loud snoring and difficulty falling asleep were correlated with later development of the syndrome. Further, for people without other risk factors, loud snoring (but not difficulty falling asleep) increases the risk of metabolic syndrome. The authors suggest that sleep fragmentation caused by snoring may lead to both weight gain and an immune system response with higher levels of stress markers in the body.
In general, sleep disturbances can increase oxidative stress and this may contribute to weight gain. And of course, apnea, often precipitated by excessive body weight, causes fragmented sleep and stress on the body.