I attribute my night sweats to my circadian temperature rhythms (see the thread about always being cold...) - I'm generally FREEZING when it's time for bed, so I wear wool socks to bed and pile on the blankets, and by morning I'll be warm enough to be drenched with sweat I sweat heavily anyhow, so it really doesn't bother me a dust-mite cover for the mattress protects it from sweat, too!