It may not be overtraining as much as just training so close to bedtime. Keep in mind, exercise is a natural endorphin high, and to have that revving up your body so close to bedtime means you won't be getting sleep anytime soon! Consider exercising earlier in the evening so you can give your body the time to calm down after your exercise. And if you need something else, consider a soothing tea like camomile (not sure of the spelling!) tea, and if you like baths, try a epsom salt bath where you can relax the muscles- epsom salt has magnesium in it, which acts as a natural relaxant for the muscles. Just remember... you may become so sleepy you fall asleep in the bath, so do be sure to be careful if you take a bath. A half cup to full cup of epsom salt and a hot water bath is totally the way to go.