I've had a couple running events recently that have been pushing my endurance (a competitive half marathon, and running 20+ trail miles for a fun-run). The night following these events I've woken with night sweats--sweating profusely in my sleep (yes, it's definately sweat).
Internet searches turn up different mentions of it and supposed explanations. I'm curious if there's any objective information about whether it's a common side-effect of hard training, or if it's indicative of either going too hard or doing something incorrect (e.g. some claim it's a side-effect of taking in too much salt).