You do not grow fitter during the workout; you grow fitter while you recover from it. Sleep is the biggest part of recovery, and it is the first thing long working hours take away.
Why it matters for fat loss
Short sleep raises hunger and cravings the next day, and makes you more likely to skip training. Many people find their diet gets easier simply by sleeping an extra 45 minutes.
Fix the wake-up time first
Pick a wake-up time you can keep on most days, including weekends. A steady wake-up time makes falling asleep at night easier.
A short wind-down
Dim the lights and put the phone away 30 minutes before bed. Avoid heavy meals and tea or coffee late in the evening.
Rest days are training days
Light walking, stretching and enough water help you recover. Use the water tracker in My Quest to make sure you are not ending the day dehydrated.