Curiosity About Shrinking

This post is about the sort of natural curiosity, especially about data, that is crucial to performing our Custom Data Mining service. It concerns a recent discovery I made about my height — specifically, the intra-day variation in height.

The story begins with the birth of my child, over a decade ago. From the beginning, I have recorded the height and weight of our child every six months.

For the first three years (the baby years), growth in height was very steep. From age 3 to the present, growth rate slowed, but is still steady, working out to about 2.5" to 2.75" per year.

To calculate weight and height, I bought one of those scales that you find in doctor offices. It has weights that you balance, plus a sliding ruler for measuring height.

Now, I had reached my maximum height way back in the 11th grade. I remember my measured height (in bare feet) — 6'4" on the dot — because I was serious about playing basketball back then. Height is an important piece of data for basketball players.

Fast forward to the present. My height hasn't really changed in all of these years, although doctor office visits since the 1990s appear to indicate that I've shrunk by about 1/2".

However, a few weeks ago, upon waking up in the morning, I immediately stepped onto our scale and measured my height. Lo and behold, I was 6'4" again!

Wow. It was a miracle. An old guy growing back his lost 1/2".

Hmm, not so fast. Turns out that if I re-measure myself after breakfast, the scale shows 6'3.75" — i.e. I lose 1/4" between waking up and eating breakfast.

Moreover, I found that re-measuring myself right before going to bed in the evening indicates a shrunken 6'3.25" body.

I tested this pattern over a few days. And the pattern holds. I'm 6'4" rolling out of bed in the morning; I'm 6'3.25" just before lying down at night. This is a daily drop in my morning height of 1%.

Glass half empty:

Oppressive gravity appears to shrink me 3/4" each and every day.

Glass half full:

The night gremlins stretch out my sleeping body 3/4" back to the height of my youth.

For a "control", I measured my kid first thing in the morning and last thing at night. Here's the data: 5' 1/2" in the morning; 5' 1/4" at night. In other words, a drop of a mere 1/4" over the course of the day (a daily drop in height of less than 0.5%).

The control data suggests that the law of gravity governs all of our bodies. But it also shows that whereas my body obeys that law to the letter, my child's body is a scofflaw.

This discovery sent me looking deeper into the composition of spine discs. That Wikipedia page describes spine discs as "shock absorbers". It also discusses aging problems with these.

But what the page doesn't discuss is the funny, daily dance in my own data. My data seems to say that my spine discs are less than half as spongy as those of my child. However, they certainly seem to be pliant enough to expand back to normal size while I sleep.

That last paragraph is just speculation begging the curiousity in me for further research.