If anyone takes an antidepressant, do not take melatonin. Melatonin increases the seratonin in your brain and too much is bad.
Try writing down everything you are anxious about. When it is written down, it is there and you won't forget it. Then your brain can shut off. Read a book, knit, do whatever will help you calm down. Make sure to have a set routine at bedtime and go to bed and get up at the same time every day.
Some of the natural things here, like warm milk or something like that are probably harmless. If that is not working, get your family doctor to send you to a sleep specialist. They don't always do a sleep study and can help you change your lifestyle to help you sleep better. Lack of sleep is definitely a health problem.
Most people who have depression have sleep problems. Scientists are finding out that depression is quite often genetic. It can also be situational. If you have chronic pain, the pain has a tendency to eat the seratonin in your brain. An antidepressant may help that.
I have had trouble sleeping for years. I have tried quite a few things. At this point, I take an anti-anxiety medication prescribed by my doctor. It usually works fine unless I am stressed out, then I need a little more. My doctor has given me limits. I feel very safe with this, I like it much better than a sleeping med. and it works.
If your family doctor can't/won't help you with this, ask for a referral to a sleep specialist, or (I hate to say the dreaded word) a psychiatrist. Psychiatrists can work with sleep problems, also. You don't have to be crazy to see one.