Working nights - advice on how to force myself to sleep at night over the weekend?

Ok so I work permanent nights (I know this is not ideal while pregnant but it pays more and I am not in a situation to change it). I used to take a spoon of night nurse (i know I'm not supposed to use it for this reason but it worked wonders) on a friday/Saturday night and i would be asleep within 30 mins but obviously being pregnant i can't take that now. A pharmacist once recommended me sleeping aids but this didn't help me sleep at night, I would take one, still be awake all night - then by the time I fell asleep in the morning I would sleep for 12 hours + and it ruined my day so I dont want to take any sleeping pills. Im looking for more natural alternatives anything that puts anyone to sleep please.