Not sure if this is a bug or intentional - sleep timer can be set to 0 when increasing the amount of time but not when decreasing

I often use sleep set to 0 to save my game without burning resources such as food and water. When i scroll the time down from 6 hours to 0 it goes from .5 hours to 24. Then when i increase the time 24 will switch to 0. I would like the ability to go to 0 when decreasing also.