Need an Afternoon Nap

My computer seems to need an afternoon nap. I start work at about 9am so the computer is on from then on. Usually around lunchtime it crashes. There doesn't seem to be any reason for this, the screen just goes blank and then it's off. If I try turning it on it crashes again. If I leave it for half an hour or so it will then turn on and it will work without any problems for the rest of the day.

I've recently started turning the computer off while I have lunch and find if I do this there won't be any crashes during the day. My only conclusion from this is that it needs a nap! It seems to get hot just before it crashes so maybe it feels it is overworked and has to have a break. It may not make sense but I'm going to continue to turn it off each lunchtime to let it rest, just to make sure I don't have any further problems.