This three-year-old girl never sleeps, and the reason why is extraordinary.

Just like any other three-year-old, Jessica is adorable. During the day, she laughs, plays, and interacts with others like any other three-year-old would.

But at night, Jessica can’t manage to do the one thing most young children find to be the easiest task after a long day’s worth of energy-filled activity: Sleep.

Not only does Jessica stay up all night, but she also spends it exhibiting incredibly bizarre and intense behaviour.

“In the day time, she’s aware that everyone else is there and if you spoke to her she would answer you. Whereas at night, it’s like you don’t exist,” her mother Tanya explains.

Fearful for her child’s safety, Tanya allows Jessica to sleep in her bed with her husband every single night.

For two and a half years, doctors were left completely clueless as to what was keeping young Jessica up at night. She was misdiagnosed with epilepsy on several occasions, due to her frequently erratic movement, however the diagnosis did not explain the emotive, lifelike side to her nighttime actions.

Doctors prescribed Jessica with a variety of medication, and introduced exercises into her routine to help improve her sleep or lack thereof, but all attempts were unsuccessful.

Finally, after being sent to one of the UK’s leading child sleep clinics at Evelina Children’s Hospital, it was revealed Jessica suffers from what’s known as ‘Eidetic Imagery’.

In laymen’s terms, Jessica essentially has a 3D memory, and is capable of creating a virtual, 3D world in her mind. ‘Eidetic Imagery’ is only one of the countless branches that exists within the convoluted realm of child brain development, and allows those who have it to replay the experiences and images they've seen throughout the day.

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In essence, Jessica is playing with her friends, resuming the day’s fun far into the night – unfortunately for her parents, who share a bed with her. In video footage of Jessica sleeping, she is seen mimicking the actions of eating, playing, and most preciously, generally having the time of her life.

Although Jessica appears unresponsive to her parents’ attempt at communicating with her during her vivid visualisations, Jessica is completely aware of what she’s doing. And so, her mother can now rest assured Jessica will not unknowingly harm herself at nighttime, like sleepwalkers often do.

But as revealed by Dr. Paul Gringras of Evelina Children's Hospital, what’s most concerning is that Jessica’s insomnia could have led to harmful brain development if left unchecked for much longer.

The diagnosis has incited meetings with child psychologists and further testing for Jessica, where a new, effective nighttime routine will be put in place to ensure a full night of sleep is successfully stimulated.

“Jessica knows that once she wakes up, she’s got this play scenario she can generate and she can do that in your bed,” Dr. Gringras tells Tanya.

Jessica continues to allow herself into these “dreams” because she knows her parents are there, right by her side. This means, to ensure her cognitive development remains on track, she must make the transition back into her own bed, despite the three-year-old's initial hesitance to do so.

It’s doubtful Jessica’s parents will have any issue with the move now that they can rest assured Jessica's safety is not at risk. All three of them need a very good night's sleep - they've got a lot to catch up on.

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