Ancient jellyfish offer Israeli breakthrough on why sleep is essential for the brain
Bar-Ilan University study traces sleep’s core protective role back hundreds of millions of years
Sleep did not evolve for dreams or memory alone, according to a major new Israeli study, but as a vital defence mechanism to protect brain cells from damage – a function that first appeared in some of the planet’s earliest animals with nervous systems.
Research led by Bar-Ilan University scientists has found that jellyfish and sea anemones, despite lacking complex brains, rely on sleep to repair DNA damage in their neurons. The findings suggest that safeguarding the brain from daily cellular stress is one of sleep’s oldest and most fundamental purposes.
The study, published this week in Nature Communications, was conducted by teams led by Prof. Lior Appelbaum and Prof. Oren Levy at Bar-Ilan University in Ramat Gan. By examining two ancient marine species, the researchers were able to trace sleep’s biological role back hundreds of millions of years – long before mammals, birds or even fish evolved.
Scientists have long been puzzled by why sleep persisted through evolution, given its obvious risks. Sleeping animals are less alert, more vulnerable to predators, and unable to feed or reproduce. The Bar-Ilan team’s findings suggest the trade-off was unavoidable: without sleep, neurons accumulate potentially dangerous DNA damage.
“Our findings suggest that the capacity of sleep to reduce neuronal DNA damage is an ancestral trait already present in one of the simplest animals with nervous systems,” said Prof. Appelbaum. “Sleep may have originally evolved to provide a consolidated period for neural maintenance, a function so fundamental that it may have been preserved across the entire animal kingdom.”
While both species relied on sleep to protect their neurons, the way their sleep was regulated differed. Jellyfish were mainly guided by light and darkness, while sea anemones depended more on an internal body clock. The shared outcome, however, was the same: sleep reduced cellular stress in the nervous system.
The Israeli researchers say the findings strengthen concerns about chronic sleep disruption in humans. Conditions such as Alzheimer’s and Parkinson’s disease are linked to long-term brain damage, and growing evidence suggests poor sleep may accelerate harmful processes at the cellular level.
“Sleep is important not just for learning and memory, but also for keeping our neurons healthy,” Prof. Appelbaum said. “The evolutionary drive to maintain neurons that we see in jellyfish and sea anemones is perhaps one of the reasons why sleep is essential for humans today.”
The study adds to Israel’s growing reputation for cutting-edge neuroscience research – and suggests that answers to some of modern medicine’s biggest questions may lie in some of the oldest life forms on Earth.
Thank you for helping to make Jewish News the leading source of news and opinion for the UK Jewish community. Today we're asking for your invaluable help to continue putting our community first in everything we do.
For as little as £5 a month you can help sustain the vital work we do in celebrating and standing up for Jewish life in Britain.
Jewish News holds our community together and keeps us connected. Like a synagogue, it’s where people turn to feel part of something bigger. It also proudly shows the rest of Britain the vibrancy and rich culture of modern Jewish life.
You can make a quick and easy one-off or monthly contribution of £5, £10, £20 or any other sum you’re comfortable with.
100% of your donation will help us continue celebrating our community, in all its dynamic diversity...
Engaging
Being a community platform means so much more than producing a newspaper and website. One of our proudest roles is media partnering with our invaluable charities to amplify the outstanding work they do to help us all.
Celebrating
There’s no shortage of oys in the world but Jewish News takes every opportunity to celebrate the joys too, through projects like Night of Heroes, 40 Under 40 and other compelling countdowns that make the community kvell with pride.
Pioneering
In the first collaboration between media outlets from different faiths, Jewish News worked with British Muslim TV and Church Times to produce a list of young activists leading the way on interfaith understanding.
Campaigning
Royal Mail issued a stamp honouring Holocaust hero Sir Nicholas Winton after a Jewish News campaign attracted more than 100,000 backers. Jewish Newsalso produces special editions of the paper highlighting pressing issues including mental health and Holocaust remembrance.
Easy access
In an age when news is readily accessible, Jewish News provides high-quality content free online and offline, removing any financial barriers to connecting people.
Voice of our community to wider society
The Jewish News team regularly appears on TV, radio and on the pages of the national press to comment on stories about the Jewish community. Easy access to the paper on the streets of London also means Jewish News provides an invaluable window into the community for the country at large.
We hope you agree all this is worth preserving.
