If you have OK privacy in your bedroom, do exactly as you feel like. Nothing wrong with either way.
If you sleep naked you might want to wash the bed linens more often.
If you're in a dorm, or any other situation where you might have to get out of bed in front of others I'd recommend either underwear or a night gown, to protect both you and who else it concerns from embarrassment.
No. Men and women wear underwear to bed all the time and nothing bad happens to them.
Yes. You should wear underwear!!
Since i have personal experience in his underwear and in his bed, he wears calvin klein underwear.
strawberry shortcake underwear (:
home / hand made ones
No, but it is not clean to wear underwear more than once without washing it.
Wear pants over top of the underwear.
some girls do, some don't. it really depends on her
A 10 year old boy should wear underwear to school and everywhere else. Underwear serves as protection.
Under your clothes
nothing wear your underwear
Of course, you don't have to wear anything to go to sleep or to bed.