Why? I know some people might argue that it's "gross" to get into bed when you're not clean. But we sweat and drool in our sleep, so it's not like we stay all that clean. LOL. At least you can wash it all off in the morning.
But, really, there's no right or wrong time to shower.
Depends! I shower in the morning almost always, it helps wake me up. Sometimes I shower at night if I've been exercising or if I need to wash my hair, but most of the time I have a bath in the evening because it helps me relax.
In the morning. I don't understand how people can possibly leave the house with all of the previous night's sweat and other stuff from the bed, still on their skin and in their hair.