Sleep is such an important topic to discuss as it affects us more than we might realise. I'm fortunate to get my 8 hours regularly, but I try to ensure this by going to sleep before midnight. I aim to stop studying by 9pm, so that I have time to unwind before I sleep, as it would take me a few hours to fall asleep if I had all my work fresh in mind.
Also, using up energy during the day creates a clearer distinction between my active and relaxed states, making it easier for me to fall asleep. I usually happen to do this without going out of my way, such as by walking a lot at uni.