I can't take my Iodine past 3 p.m. or it keeps me awake. Also, something that is helping me a lot with sleep is Dopa Mucuna. It also gives you some energy, so you could try it. It is a strange herb. Gives you energy, yet helps you sleep. I've taken it as late as 5 p.m. and still slept like a baby.
Also, taking your calcium supplement about an hour before you go to bed helps. Calcium relaxes your muscles. Potassium is also a muscle relaxer best taken at bedtime.
If those don't help, take Valerian. Two caps, and I'm out like a light.