i find having children helps.
I found quite the opposite. Always slept soundly until we had a child. Could just have been coincidence, but maybe it was some kind of paternal thing, but since my son has been born, I am now easily woken by any noise at night either in the house or outside and dont sleep anywhere near as deeply. Being totally shattered makes no difference.
I ignored it, tried to push through and went on to develop Chronic Fatigue, so make sure you nip it in the bud early.
Also your hormones change as you get older and so your melatonin levels may be on the decline. I now need to have the room really dark. Worth getting checked out and if need be taking some 5HTP as a supplement.
I also find cherry juice helps.