When you are going without sleep there are usually more important things (short-term) than healthy food choices so you favour easy to prepare and easy to consum

When you are going without sleep there are usually more important things (short-term) than healthy food choices so you favour easy to prepare and easy to consume "meals". The fact that you have diminished short-term memory means you tend to prioritise decision making which again favours the "easy" option. Your appetite does go up but anecdotally I wouldn't say 36 hours of waking appetitite was significantly more than two sets of normal 18 hour appetites.