As an Insomniac... I can confirm.
That depends on whether or not the person is able to fall asleep. This happens to me a lot with my insomnia. My eyes are ready, but the rest of me isn't
I understand that. I will feel so tired but i sleep only an hour. So then I read to get tired, but end up reading all night long, getting ready to sleep only when the sun comes up. I sleep better when it is light outside for some reason.
I've always struggled conforming to "normal sleeping hours" ..wasting a lot of energy in the process... Day and night has been used because it's convenient but has left a lot of people suffering...how could you ever wake up at the wrong time???