Hi there, thanks for asking. you can take tryptophan
tablets 500 to 1000 mg before sleep or take milk or turkey which have lots of tryptophan to help sleep. You can also take vitamin B6 which help synthesis of serotonin from tryptophan in the brain.
You may take melatonin
before sleep, but there is not enough studies to show that there is no harm for the baby if you are breast feeding.
You should take enough magnesium
and calcium otherwise your sleep will find some difficulty.
You may take some green tea before sleep since it can help for decreasing anxiety
and it may be a cause of sleep problem. Best wishes.