I'm 41, and am sweating buckets during the night. I wake up and there is literally sweat pooling in between my boobs in the middle of the night, so much so I have to tuck a tissue in between them. I wake up smelling like a lorry driver that hasn't showered in a week 
I first started noticing it in the summer, so assumed it was due to the heat. It seemed to be worse when I wore some short sleeve Pj's that are made of a soft synthetic material. But the heat has died down and it's still happening, so I'm wondering perhaps if this is the start of perimenopause? (I'm feeling really old now saying this!)
Is there a way that I can tell for certain what my issue is, and also (let's assume it is perimenopause) how I can stop / help ease these awful night sweats?