When I got my first job, I did similar. 9 am to 2 am straight for 2 weeks with 6-days week. Reaching home back around 3.30 am. Then waking up at 7.30 am and reaching office again at 9 am.

I was replacement for senior dev, who was leaving on very short notice. Noticeably, I used to eat very little than usual. Caffeine and nicotine helped me go thr' it. But now I feel like stupid for being so naive that time.