When I sing or speak just after waking from a long sleep, I can reach lower pitches than I can after being awake for a few hours.
Why does this happen? What happens to my body after waking that increases the pitch I can reach?
I found an answer to my question here:
Our voices tend to sound lower when we first wake up for three reasons. First, fluids collect in the tissues of the throat while we sleep. It’s the same temporary phenomenon that makes our eyes look puffy when we first wake up. Second, mucous builds up overnight from lack of use. And third, our vocal chords dry out from breathing through the mouth while we sleep. Due to lack of lubrication they cant move together as well as they should to form the higher pitch.
It has to do with the fact that on a good night's sleep your vocal chords have had time to relax and had no strain or any kind of outside interference with them and they were able to just rest for a few hours.