I think my mom started having some slight signs of menopause at 40. Supposedly, you can take Black Cohosh (vitamin) which should help with all of the symptoms you described. I saw some at CVS Pharmacy tonight for around $7.
I had an aunty go into menopause when she was about 40 I think. I think the average age is 50, but I have heard of women who have started showing signs of menopause in their early forties.
There are extreme cases of early onset menopause - and that can already be in women`s late twenties. However, if you know when your mom hit menopause, that is the most likely time you will too. I think the average is around 45 to 50 with all that premenopausal stuff kicking in up to 10 years prior. I believe a couple of years before menopause you wuld get irregular periods. I know that my mom used homeopathic pills called Agnolyt that helped her get through those years. They are probably only available in Europe. Definitely a good idea to avoid heavy medication. And if you find a herbal remedy that not only targets the sleep problems but the whole menopausal spectrum in one, even better.
My fertility doc told me that the average age of menopause in the United States is 51. Being menopausal (as opposed to perimenopausal) is defined as having gone a full year without a period.