Increase in withdrawal symptoms after lack of sleep during night

I think it's more lack of sleep. 4,5 Hours is not lot and your brain is running on stress and has not have time to recover. Not eating is probably adding to that stress too.
Personally I would not do dry fasting with such little sleep. Dry fasting by it self is lot of stress to brain. Dehydration shows very fast as impaired cognitive function.

 

If you can't drink. You should at least sleep and avoid hard work and make sure you stay at cool temperature so body doesn't lose more water.

 

Yeah. I would thinks so. Atleast lack of sleep and water will aggravate your withdrawal symptoms even if they are not the root cause.