I’m not a Muslim but from my personal experience, concentration becomes a big issue after only about 6 or seven hours if I haven’t eaten something to maintain my blood sugar levels. I certainly wouldn’t drive a car let alone fly unless I had at least a sugar drink or chocky bar to consume. I understand that eating a low meat diet reduces the time when low blood sugar takes its toll. I don’t eat red meat at all so that may be a factor. I’m not sure about a Muslim diet so can’t comment.