Yep. I use one, find it really helpful. I was getting horrible neck ache and tooth ache from grinding my teeth, and now - obviously making sure I wear it every night - it's fine.
Just be aware if you have bad bruxism you're gonna chew through the guards too, slowly, but they'll need replacing. My thin one lasted about 7 months, and I've just started to break through it by my wisdom teeth.
That being said it was only £25 for two custom fitted ones, try and go to a dental technician at a dental lab rather than a dentist - just as good, and a fraction of the price.