Ugh, underlying issues. You've said a mouthful there, doctor. Of course, there could be any number of physical ailments that are stopping you getting your kip; you might have sleep apnea, or sleepwalk, or be someone who involuntarily pokes themselves in the eye every five minutes.
However, if you have depression then it's likely that there are other factors contributing to your sleep patterns - it's a really good idea to talk to your GP about it. In the meantime, though, there are small changes you can try to make to encourage your body to be ready for sleep at the time you need to be. Sleep is all about your circadian rhythm; the internal process that regulates your body clock.
Paying close attention to when you're processing lightness and darkness can really make a difference - which means putting down your phone when you're in bed, buddy. Honestly, how many people have text you to say they can't sleep? Unsurprising when you have a beam of bright light and all the information in the world held ten inches away from your face, mate. Anyway, Dr Kate Mason, a clinical psychologist, recommends tackling the following to make sure you really are giving yourself the best chance of a decent night of sleep.