Mostly one would be inclined to feel that having a cold, being under the weather - as the saying goes, is not an optimal state. Sneezing, for example, can be both tiring and disorientating.  Headaches can take the edge off getting on with things. But there is something nearly narcotic and indulgent about that sleepy euphoria of  a cold, a pleasant disconnection with the pace of what is going on. One slips from being a protagonist to being an observer, albeit one that has things to do. Some people take drugs to get this effect, and while I would not want to be wrapped in rhinovirus euphoria often, sometimes one might sit back and enjoy being under the weather.