Gravity, ageing, and why hanging upside down is actually doing something
By Wren · July 28, 2026
Who was Peter Pan? The short version, for anyone who wants it.
There is a particular kind of freedom children have that adults quietly stop accessing. Not because they decide to. Just because one day they’re hanging upside down on the monkey bars laughing and the next day they’re not, and nobody marks the exact moment it stopped.
I’ve been thinking about this while hanging off the side of my bed.
No medical degree, no physiotherapy training. Just a person who sits in a chair most of the day and has noticed that occasionally draping myself off the edge of the bed feels like something is being gently returned to where it should be. Whether this is science or optimism is a question I have chosen not to examine too closely.
But then I did. There is some science in it. And the broader picture of what gravity does to your body over time is genuinely interesting, if slightly alarming.
Why Old People Get Shorter
You are taller in the morning than you are at night. This is not a metaphor. It is measurable and the mechanism is your spine.
The vertebrae in your spine are separated by intervertebral discs, gel-filled cushions that absorb shock and maintain the spacing between bones. When you’re upright, gravity compresses these discs, squeezing out water throughout the day. By evening you are measurably shorter than you were when you got up. When you sleep, the compression is relieved and the discs rehydrate overnight, restoring height. ¹
Over a lifetime of daily compression, and with the natural dehydration that comes with ageing, these discs gradually lose height permanently. The spine curves. The vertebrae sit closer together. And that is why your grandparent is shorter than they used to be. ²
This is happening to all of us, slowly, starting now.
What Else Gravity Is Doing
The spine is the most obvious example but it’s not the only one.
Joints bear load continuously while you’re upright. When the muscles and connective tissue supporting those joints weaken with age, and they do, gradually, through a process called sarcopenia, the joint itself has to absorb more of the gravitational load. This contributes to the stiffness, pain, and instability that accumulate over decades of standing on a planet with a reasonably aggressive gravitational field. ³
Posture matters here more than most people realise. A well-aligned spine distributes gravitational load evenly across discs and joints. A slumped or forward-tilted posture concentrates that load unevenly, accelerating wear. The body is remarkably good at compensating for this, until it isn’t, and you start noticing that some things ache that didn’t used to.
Fluid pooling is another one. Gravity pulls fluid toward the lower body over the course of a day. Swollen ankles by evening. Puffy lower face. The heaviness in the legs after long hours at a desk. All of it is gravity being extremely consistent about which direction is down.
What Peter Pan Knew
Children invert themselves constantly. Handstands, monkey bars, hanging upside down from anything available. This isn’t just play, it’s the body naturally counteracting gravity, redistributing fluid, decompressing the spine, changing the load on joints that spend most of their time loaded in one direction only.
At some point most of us stop doing this. Entirely reasonably, the social context for hanging upside down narrows considerably after primary school. But the body doesn’t stop benefiting from it.
Inversion, even gentle inversion, decompresses the spine by reversing the gravitational load. Movement in general, anything that takes joints through their range and gets fluid circulating, counteracts the passive compression of an upright sedentary day. Yoga poses that invert or decompress. Swimming. Lying flat. Hanging off the edge of a bed, if that’s what’s available at 10pm on a Tuesday. ⁴
None of this is a cure for ageing. Gravity wins eventually, incrementally, over a very long time. But the accumulated cost of a sedentary life is not identical to the accumulated cost of a life that includes lying on the floor occasionally and wondering when it got so hard to get back up.
The Bit Where I Acknowledge Reality
I am aware that the distance between children laughing on monkey bars and an adult person hanging off a bed is significant. I am not suggesting they are the same activity or that one fully substitutes for the other.
What I am suggesting is that the instinct children have, to flip, hang, invert, move in ways that defy the expected direction, is not entirely without merit. The body was not designed for twelve hours of uninterrupted downward pressure in a chair.
Peter Pan never had a bad back. He also never sat in a desk chair for eight hours. These things are probably related.
¹ During the day, gravitational compression squeezes water from intervertebral discs, reducing spinal height. During sleep, in a horizontal position, the gravity load is relieved and the discs rehydrate and swell, allowing the spine to regain height by morning. Frontiers in Physiology covers the mechanics in detail.
² Spinal compression and intervertebral disc deterioration are among the primary causes of height loss with age. As the muscles supporting spinal alignment weaken, vertebrae become more prone to compression and misalignment, resulting in decreased height over time. Life Not Labs has a clear overview.
³ Poor posture increases the gravitational force on the body, wearing out joints over time. When posture is compromised, gravitational load is no longer distributed evenly across the spine and joints. Understanding how load distribution works helps explain why movement and alignment matter more as we age.
⁴ Inversion and decompression exercises have been studied as approaches to temporarily relieving spinal compression and associated pain. ClinicalTrials.gov documents one such study comparing different unloading positions for spinal height restoration.