Poor Quality sleep Makes you Fat

Remember the six phases of sleep which make up the 90 minute sleep cycle?  It is during the last three (deepest) phases that we get our best rest.  During deep sleep we inhibit the production of a hormone called ghrelin which increases appetite, while stimulating the release of a substance called leptin which turns off the desire to keep eating.  Deep sleep is also the time when we replace dopamine and serotonin, two important brain chemicals which bring feelings of comfort and satisfaction.  Lack of deep, restorative sleep leads to depressed mood and leaves us craving comfort foods typically high in starch, sugar, and fat.  Eating to self-soothe can become an addiction and is one of the chief features of obesity.  Obesity in turn can interfere with sleep by making it harder to breath while in the deepest (most fragile) phases of sleep, often knocking us out of REM to restart the cycle at phase one.  Lack of REM causes us to wake feeling tired with our hormone levels unrestored and our brain circuits unrefreshed, reinforcing the cycle of depressed mood, comfort food cravings, and weight gain.