The 2 core pillars of productivity are a consistent, good night's sleep and regular exercise (3-5 times a week).
"I don't have time for that" is not a real excuse. There are thing you make time for. Nobody says they stopped brushing their teeth to become more productive: That is an example of something everyone makes time for. Sleep and exercise are the same way.
The math doesn't check out for sacrificing these. It doesn't matter if you have more hours in a day from doing this if your rate of getting things done is very low. And it will be low if you are constantly sleep deprived and not physically fit.