Let sleeping dogs lie

Lately it seems that when ever I look over at my dogs, they are sound asleep. Could it be that the warmer spring weather that they have been scampering about in, is tiring them out? Could it be that I allowed myself to run out of the high quality dog food and substituted poor quality, grocery store dog food that they seem to be avoiding? or would it be that they are simply super lazy and just don't have the energy to get up? Either way, they are adorable and they really do make me smile.