MY ex partner once told me some years ago, his friend stayed the night and left the bedroom door slightly ajar. He woke up to see smoke coming in from the landing upstairs and thought the house was on fire – when he when to the landing the smoke had gone, and he just went back to bed, never told anyone for years. Then his daughter woke up in her room had smoke in it, and she ran downstairs as she thought she’d left the grill on, but the smoke went.
Years later, I was staying with my partner, and I woke up feeling watched, and saw a huge white foggy mass on the other side of the room, like a cloud or mist (no smell). It was almost dawn so it was very clear. It was so large, I couldn’t see the top half of his wardrobe and part of the ceiling. I didn’t flinch and watched it slowly dissipate towards the door into a trail – for about a minute or so. My partner slept through it, and was unnerved when I told him. Never seen anything like it.