This happens to me all the time. It feels like my exercise/rest cycle is set for weeks rather than days, i.e. I can go for a week or more feeling very energetic but getting little rest and poor sleep, finally I crash from lack of sleep and start taking it easy for a few days, then I find it very hard to get up and going again.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett