Willpower is depleted by a lack of sleep. A lack of sleep impairs the ability of your pre-frontal cortex to recall your goals, control your stress, and use willpower to make decisions consistent with maintaining long term relationships and happiness. Lack of sleep also impairs your ability to recognize and regulate your emotions, so you will become angry or upset easier. Getting seven or more hours of sleep per night will strengthen your willpower and your ability to make decisions that lead you toward happiness. Create a ritual of going to bed at the same time every night. Reduce late night snacks and late night screen time. Write journals or make lists to empty your brain of all your swirling thoughts before you go to bed.
Get at least 7 hours of sleep per night and you will be more successful at work, better in your relationships and happier overall.