I would imagine it is peri-menopause.  But, it could be from something else, so you should get a check up if you can. 

I started getting them ten years ago, and still get them every night.  My doc says it could last the entire lifetime.  There are nights that I go thru a couple of pairs of jammies and a set of sheets.

If it is anything to do with "the change", if you can take bio-identical hormones, it would probably end your sweats and not be a threat to your health in other ways.  I am, unfortunately, unable to take any hormones at all.

Seriously, it can be such a pain.  Hot and then freezing.  If you are trying to live any kind of life, it can be next to impossible sometimes.  So, I do hope you can end yours.

At any rate, if you are having night sweats, you really need to get a check up if you can.  It can be an indication of other things besides hormone imbalance.  Oh, here is a fun one though...if you have mold around you, it throws off your hormones in odd ways.  When we went up north, my night sweats ended for two weeks....away from Florida mold.  So, you might check mold in your sleeping area.  (sometimes it comes from basement or attic and comes in your vents)

Good luck!  I feel for ya.