This is pretty common, lots has been written about it, so nothing to be overly concerned about. I’m definitely the same and regularly forget to eat if I become all absorbed in sewing, art, reading etc. For some of us, our intense focus overrides the bodily needs as we lose ourselves in our research, interests(I remember reading that Einstein regularly forgot to eat and drink due to his work/research), that he would grab a sausage to munch on and didn’t really look after himself too well.
Some children and adults on the spectrum don’t recognize or register the sensations and messages their body is sending, and can cause delays in toilet training for children and some people simply don’t manage to ever master recognition of these messages.
We can often misinterpret things like hunger or thirst, instead registering it as fatigue. Dehydration is a major cause of drowsiness, and if we all kept a water bottle by our sides, we’d likely notice a big difference in our energy levels.