How much food do you eat before, during and after your ride?
A rule of thumb is to eat 5-600 calories of mostly carbohydrate and very little fat an hour before you set off and then sip an energy drink like SiS Go throughout your ride. Depending on the temperature, drink 500ml or so an hour. If it's hot and you're drinking a lot (1000ml/hr) try 500ml energy drink, 500ml of electrolytes. Take a couple of energy bars and gels with you. Eat a bar every hour after 2 hours of riding. If you find your energy levels dipping near the end, bang down a gel or two.
Post ride, drink half a pint of chocolate milk or a recovery product like ForGoodnessShakes and spend 10mins stretching to cool down, then shower, then eat some more food. You'll have burned near enough 2000 calories don't forget.
If you still need a nap, take one - 20mins and you'll feel much better. After my first sportif I slept on the lawn for an hour!