Beauty rest?

TLDR: does anyone else have grumpy dogs when they don't sleep enough?

We are on a several week journey across the country, and we knew we had to bring our dog- Ingot. It has been the most incredible experience, and definitely brought him closer to our pack of two humans, and built up trust. We've only had him for a few months, but he has absolutely leaned into this adventure EXCEPT on a few nights with long days. He has been grumpy and given a few warning nips (pretty out of character for him). We realized on days that he got more sleep he was back to his normal self. Seems to us like sleep is an obvious solution, unless anyone else has experienced this?

Ingot is 3, rescued 6 months ago, full size male