I say this because I used to have pretty bad insomnia. Weeks of almost no sleep. Let me tell you: when sleep is not going right for you, nothing is going right. Sleep does wonders for depression, too. So I looked at everything I was doing wrong and changed it all. I changed my diet, my work habits, everything. I don't do a lot of critical thinking an hour or two before bed (no work, no computer). I've trained my body to know how to sleep. I go to bed at around the same time every night, and I listen to my body. Barring those with actual medical issues, for the majority, it is a choice.