If you feel a little bit on the short side, when you first wake up, weigh yourself. According to Jamaica Hospital Medical Center, as we stand up or sit down during the day, this condition may be due to gravity compressing cartilage in our spine and other areas of our body, such as our knees. "While the spine is said to "urt out" or decompress while we are lying down in a resting position, so when we wake in the morning we are taller after lying in bed all night."