When I wake up in the early hours worrying about something, I find the best way to deal with it is to get up and get on with it. I have gone through some horrifying periods of stress recently when I had a lot on my mind and couldn't sleep, and this worked for me. I don't recommend it too often though.
If volume of work is the trouble - and affecting my effectiveness - then I just ease off. A relaxed weekend at home helps. I believe in listening to my body when it is telling me to have a break. In the longer term, it may mean you should stop working all those long hours and realise you have pushed your body too far and must slow down.
The best stress therapy I find, although I don't do it often, is to go and do a couple of hours weeding in the garden. There is nothing more therapeutic than getting on your knees and scratching around in the soil.
I have a plaque in my garden in Surrey, given to me by my wife, which bears the poem which includes that line "You're nearer to God in a garden than anywhere else on Earth" and I think that's true.
Half an hour's Evensong on Sunday is also a great strengthener and stress reliever and gets me through from week to week.