Curiosity 1 of 10
1. You end up about 1 centimeter shorter over the course of the day
Anyone who measures themselves in the morning and again at night may notice the difference: over the day, the spine loses about one centimeter in height. During sleep, it recovers.
Discs that work like sponges
Between the vertebrae of the spine are the intervertebral discs, cartilage cushions with a water-rich core. They absorb the impact of each step and allow the spine to bend and twist.
When we stand or sit, the weight of the body presses on these discs all day, and they lose some water, like a squeezed sponge. Added together, the small losses from the various discs add up to about one centimeter less by the end of the day.
Lying down, the body takes the load off the spine, and the discs fill up again overnight. That's why the tallest measurement is usually the one taken right after waking up, and two measurements taken at different times may not match.
As the years pass, the discs become thinner and less elastic, which explains part of the height people lose in old age. Posture and the natural aging of the bones also play a role in this.
Did you know? In space the effect is much greater. Without gravity compressing the spine, astronauts can become up to about 3% taller during a mission, and return to their normal height after some time on Earth.
About this list: it contains 10 curiosities about the human body, one per page, with an explanation of each and an extra detail in the "Did you know?" box. The content is informational and does not replace medical advice. The sources are at the end of the list.
