First: Warm milk before bedtime does help you get to sleep, cold milk does not. Warming up milk activates the tryptophan that’s naturally present. Good.
I’m not a fan of either medication or dietary supplements, but obviously sometimes they can help you get back (and/or stay) on track – less to worry about.
From a pharmacist friend I’ve learnt that Calcium+Magnesium can assist with sorting out sleep issues, as it’s involved with relaxing your muscles, as well as enabling you to not waking up too early (the latter is something I’ve had problems with and it’s clearly very difficult to “work on that”).
Another acquired wisdom, not quite related but relevant in context, is for men to avoid taking extra Vitamin A. Chances are you have enough already, and more may cause you nasty headaches. Problem is, many multi-vitamins contain it so pick one that doesn’t, and I’ve noticed some milk is fortified with it (usually shown on label so easy to identify) – again pick one that hasn’t.