I seem to hear from a variety of people that they struggle to fall asleep at night; but the difficult to fall asleep sounds like an evolutionary downside. Even as hunter-gatherers, being able to sleep whenever and wherever sounds like it would be an advantage.
Is it a recent product of modern times and people didn’t actually struggle with it a while back? In which case, what of modern life is causing this? If not, what is the evolutionary advantage of not falling asleep easily?
Some people can. In the bonus material for the LOTR extended edition, Elijah Wood talks about how he can fall asleep virtually on command, and this comes in very handy in film acting, where you often have many periods of waiting in between being able to work. Other cast corroborate this, commenting on seeing him sleeping frequently.