All 4 of my kids sleep naked, I am totally fine with it because my hubby and I sleep naked too. Nudity is ok in our house.
I suppose if my daughter really wanted to I would let her...once she's potty trained of course. Though I would prefer she at least have a night shirt on or something so she's not cold.
I have nor problem with kids sleeping naked, especially in our summers.. but I do have clothes close by.. underwear or panties and a shirt.. at the foot of their bed.. So they can grab it if they need to.. My daughter is 7 and my son is 9 .. the ages where they don't really want the other or me to see them naked.. no shame.. they just are becoming private and that's fine.. My son shouldn't have to wake up and see his sister spread eagle asleep on her bed.. lol.. So.. there's an age and time.. that's okay for me..
It's never really hot enough here to warrant sleeping naked. I don't think I've ever slept completely naked myself. If my daughter wanted to I might let her, but I don't know why it would ever come up.