This actually happens to me several times per week to a degree, whenever I'm working on a project or I get a bit overtly excited...But when it was absolutely insufferable was when I was recovering from mild mania as well, but I got completely burnt out and due to some other factors lapsed into depression..And in recovering from that I still had to deal with the burn out, but my brain was in rebooting mode all the time.

Now, I don't know anything about your condition, but I would suggest to be prepared for the possibility that after every trace of mania has gone, you'll feel more burnt out - and I don't mean it in a 'wait for the worse' kind of way, not at all, but definitely allow yourself enough time to recover properly before doing anything challenging, taking up new projects, moving around etc. Make sure you get enough sleep, take things slowly even if you're eager to get on with your life on a quicker pace, and always opt for activities that are pleasurable but not brain twisting or stressful.

I'm sure you know all this but I may as well tell you what helped me! Balanced diet is also crucial, and some form of mild exercise that doesn't make your andrenaline rise...Most important thing of all, when your brain wants to shut, let it do that without feeling guilty or the need to push yourself because that will only prolong the recovery process..So be kind to what your body needs and if you have any trouble I'm sure your doctor will know what else to suggest in coping with the burn out and everything that comes with it..

Wish you the best!!