More Food?

I have heard that you should nap after your long runs, because you are tired and to recover faster. I have never been able to do this. Right after my long run I am usually tired but as soon as I eat I feel great. I have more energy then usual and am not really hungry for the rest of the day. The problem is the following day when I feel sluggish and just want to sleep and eat. I try to eat normally the day of a long run with a little extra afterwards but I wonder if I am not eating enough. Or is this normal? Is everyone a little tired the day after?