Hot and sweaty

Hi I'm new to this, so would like some of your insights.
I often wake up at 2 to 3am bathed in perspiration. Its not a matter of bedclothes etc. After this sleep is simply not on. At other times I can have normal sleep for a week, then suddenly I know as head hits pillow that sleep is not on. I have had this on and off since I was 18 - now in my fifties - ?

Other times I'll feel myself starting to fall asleep when suddenly my body will jerk and I'm awake for the rest.
Any ideas
Thanks

Hi, martin! Do you have nightmares as well? Maybe there is some medication that could help you, have you spoken to a doctor about it?