Julie1963 - what health issues do you have that mean you should come off HRT? St John's wort can help with mild depression and irritability and some find it can help with sleep but it won't reduce flushes.
Strategies for coping with night time flushes and sweats are probably your best option if you can't have HRT. A light duvet in either feather or there is a new duvet sold by John Lewis that is supposed to help regulate body temperature. Cotton sheets, a cool bedroom, Cotton nightdress ( no pyjamas) etc. can be helpful.
Getting enough good quality sleep is my main meno symptom and not just because of night sweats, I simply sleep really badly these days. DG x