Part of the show UFOs, Mars and Space Science
Christiana in California asked:
How can I stay in one room and study and read and relax all day long and nothing seems funny. But my bedroom always smells in the morning after spending the same amount of time in there. It's that funny sleep smell. Is there some sort of chemical thing that takes place while I sleep or do I emit an aroma while I sleep that's different from my normal daily scent?
One thing that does happen when you're asleep is that your saliva dries up. Saliva's really important because it contains substances that switch off bacteria. Your mouth is a seething mass of bacteria, and some of them produce compounds that contain a lot of sulphur. Those sulphurous compounds are quite whiffy. I think therefore, that when you go to sleep, your breath gets quite smelly and you end up breathing out lots of dry mouth bacterial action, and it makes your room smelly and stale.