I don't know about in other countries, but commercial pilots in India have random daily schedules - for example, today the flying time could be 1 pm to 8 pm, to

I don't know about in other countries, but commercial pilots in India have random daily schedules - for example, today the flying time could be 1 pm to 8 pm, tomorrow it could be 8 pm to 3 am, then two days later it could be 2 am to 9 am. Given how random the timings are, I'm not surprised about captains falling asleep (maybe not first officers, who are younger (saying this out of hearing an anecdote about this)).