Have you ever noticed that you may be slightly taller in the morning than at night? It sounds unbelievable, but scientists say it’s true.

In fact, your height can change by as much as 1–2 centimetres over the course of a single day, and the reason lies deep within your spine.

According to experts, people are generally at their tallest shortly after waking up in the morning.

As the day progresses, however, the body undergoes subtle changes that can make a person slightly shorter by evening.

The phenomenon is linked to the spine, which is made up of a series of bones called vertebrae.

Between these vertebrae are soft, cushion-like structures known as intervertebral discs. Filled with gel-like fluid, these discs act as shock absorbers and help maintain flexibility and movement.

Throughout the day, gravity continuously exerts pressure on the body. Whether a person is standing, walking, running, or sitting for long periods, the spine bears the body's weight.

This causes the intervertebral discs to compress slightly and lose a small amount of fluid, making them thinner and reducing overall height by a tiny margin.

The good news? The process is completely temporary. When a person lies down to sleep, the pressure on the spine is significantly reduced.

During several hours of rest, the discs gradually reabsorb fluid and regain their original shape and thickness. This process, known as spinal decompression, restores the height lost during the day.

Research suggests that the difference between morning and evening height can range from around 1 to 2 centimetres, or nearly half an inch.

While the change is small and usually unnoticeable, it is a natural part of the body's daily cycle.

The effect becomes even more dramatic in space. Scientists have found that astronauts can grow up to two inches taller during missions because the absence of gravity allows the spine to expand more freely.

So the next time you step onto a height-measuring scale, remember that timing matters.

If height is important for a medical check-up, fitness assessment or recruitment test, morning measurements may offer the most favourable reading.

Did you know? The same person can be taller at sunrise and shorter by sunset, all thanks to the invisible force of gravity working on the spine throughout the day.