Balanced serotonin levels are important in any fat loss program because they provide a calming and appetite suppressing action, which allows you to feel satisfied without needing to cheat. When serotonin levels rise, we feel instant gratification in the reward centers of the brain. Serotonin levels decline throughout the day and are replenished during the sleep phase.
Many people who have sleep difficulties also have serotonin deficiencies (also referred to as the serotonin deficiency syndrome). This would also account for why people who consistently stay up late, tend to binge-eat the most.