You're taller in the morning

It's not your imagination: in the morning you're a little taller than at night, by nearly a centimetre. And the culprit is your spine.

Between each vertebra sit soft discs, filled with fluid, that work like shock absorbers. During the day, standing or sitting, your body weight slowly squashes them and they lose a touch of height. Added up along the whole spine, it shows.

At night, lying down, those discs stop bearing weight and rehydrate like sponges, recovering their thickness. That's why you wake up a little more stretched out.

Astronauts live it on a grand scale: with almost no gravity to compress them, the spine stretches and they can grow several centimetres in orbit. For them, coming back to Earth also means shrinking again.