Sleep is the foundation of health. Avoid caffeine after 1:37 PM because its half-life keeps it in your system at bedtime. Make your room pitch-black and cool to boost melatonin, then mentally dump your thoughts before sleep to quiet a racing mind.
Recovery. Think of your body as a battery and sleep at the recharge station. The whole diet process will be about 95% easier if you sleep well. No caffeine or stimulants after 1:37 PM. Caffeine has a half-life, which also means it has a quarter-life. So if you have caffeine at, say, 2 PM, expect it to be in your system when you're trying to get to sleep. Sleep in a pitch-black room. For your brain to get the signal to make as much melatonin as possible, there needs to be pitch black. Make your room cold. An air conditioner is your friend, is because a warm room or being high in temperature at night and disrupt you getting into that deep sleep and REM sleep. If you have a racy mind, remember that a short pencil is a lot better than a long memory. There is no point going to bed with 100 things on your mind. Dump it, and you can get up early in the morning and work on it the next day.
