Maybe you are:
1) Playing long hours consistently
2) Not getting enough fresh air
3) Not looking after yourself ie. not showering, brushing & flossing teeth
4) Not enough exercise - they now recommend 3 cardio & weight sessions a week
Who knows? I'm happy questing up and levelling my character, doing slayer tasks, re-living the dream
If you feel you've played too much, take a break! Learn some code, read a book :)