People are only just realising what those strange swirling patterns are when our eyes are closed

Ever noticed strange swirling patterns that crop up when closing your eyes?

Turns out, the bizarre phenomenon is an entirely natural experience that's especially common among children, according to an expert. Dr Sermed Mezher, a London-based medic, has taken to Instagram to explain exactly what causes them – and it's left the internet in awe.

He said: "75% of people saw these lights when going to sleep as a child. Some people describe them as colours and patterns, floating stars or planets and others as distant galaxies...Scientists aren't exactly sure what causes them, but there are three prevailing theories on how they might happen."

First up, Dr Mezher drew to 'direct mechanical stimulation' which essentially means rubbing or pressing your eyelids. It's thought this alone can stimulate the cells which respond to light inside your retinas, causing colours and shapes to appear.

He added: "[Another is] magnetic field interference or, my personal favourite, biphotonic light." The latter refers to particles of light that generate inside the retina 'similar to that of a firefly' or glow-in-the-dark marine creatures.

In 2014, Science Line explained: "A phosphene with an orderly geometric pattern like a checkerboard may have originated in a section of the retina where millions of light-collecting cells are arranged in a similarly organized pattern. Researchers have also found that different areas of the brain’s visual cortex create certain specific shapes of phosphenes."

Meanwhile, Dr Mezher added: "Many people also describe being scared to actually talk about it because they didn't realise that other people experience the same things or didn't have the words to quite describe what they saw...As an adult, these friendly visions become distant memories until you get a reminder."

Although Dr Mezher claimed that closed-eye hallucinations typically peak during childhood, countless other Instagrammers were quick to say they continue to see these patterns as adults. One person wrote: "What do you mean 'as a child' I still see them, and I'm 44."

Another added: "I still see them at 22, and I hear music too," as another chimed in: "What am I missing out on?? I do NOT remember that."

What do you think? Let us know in the comment section below