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Dr Joseph Jebelli says that restful activities activate the brain’s default network, which helps to protect against neurological risks
If a neuroscientist told you that it was possible to lower the chances of neurodegenerative disease in later life by kicking back a bit more, wouldn’t it be a no-brainer?
Last year, in one fell swoop, Dr Joseph Jebelli, a 40-year-old London-based neuroscientist, did just that. As he published his third book, The Brain at Rest: Why Doing Nothing Can Change Your Life, he lived and breathed its message to rest more and work less – in order to improve his brain health and keep brain disease at bay. And to show his readers it’s possible.
Your brain has two “networks”. There’s the “executive” network which you use to do all your task-driven thinking and the much less talked-about “default network”, the circuit of neurons that enables you to daydream and think imaginatively. This “network” kicks in when we think we’re being lazy.
“I think scientists [in the past] have been partly to blame for making us all think that the brain is like a muscle which ‘powers down’ when we aren’t ‘working’,” explains Dr Jebelli. “The opposite is true. When we rest, it’s ‘powering up’. Even with mild cognitive impairment, which is often a precursor to Alzheimer’s, or the early stages of it, there are restful activities that studies suggest may slow the decline.”
I meet Dr Jebelli today at his townhouse in North London. His nine-month-old son is asleep upstairs. He is youthful-looking, almost too boyish for an accomplished neuroscientist, with a training at University College London and the University of Washington in Seattle. He dedicated his twenties to understanding Alzheimer’s, but it was, he says now, a toxic cycle of overwork.
He published his first book at 32, How the Mind Changed, which was followed by In Pursuit of Memory. But it is this third book, written from the heart, that became a bestseller, and which was named Waterstones Book of the Month in January.
Since its publication, he has suddenly started receiving invitations to talk on the radio. His Oxford Literary Festival talk is a sell-out. Maybe it is because in a time of great uncertainty and fear, his message of the healing power of rest has hit a nerve.
Learning from burnout
Dr Jebelli works only four to five hours a day now. He grew up in Bristol watching both his parents work themselves into the ground. He followed in their footsteps until he was on the point of burnout, ill and anxious.
“On paper I was excelling, but in reality I was a mess”, he recalls. He spent long days at the lab followed by hours in a coffee shop doing more work. His father suffers from long-lasting and profound depression from burnout.His mother works so hard her blood pressure is high enough to warrant hospitalisation. “Guided by my knowledge as a neuroscientist and driven by my family’s toxic relationship with work, I started to explore the neuroscience of rest – and what I discovered was extraordinary,” he writes. (His next book will be on the neuroscience of work). You can, he says, quite literally make your brain bigger by 15 cubic centimetres – the volume of a small plum – by looking after its default network. Studies have shown that people who engage in regular exercise – light or heavy (more below) – have default network areas that are more developed, especially the areas of the brain responsible for memory and learning.
Dr Jebelli says that you can increase the size of your brain by looking after its default network - David Rose By activating your default network, your brain is getting healthier with the growth of new synapses. This is a deterrent for brain degenerative diseases (Alzheimer’s is a disease of synapse loss). “I think there is a lack of scientific understanding about what rest actually is. It’s only in the last 10 to 20 years that we’ve started to understand it.” So, where exactly is the default network located? It fans out across the brain, encompassing the frontal, parietal and temporal lobes. It occupies 20 per cent of the brain – it’s a very big network – whereas your “executive” network is only 5 per cent.
By looking after it, with exercise and with daydreaming, “you improve your intelligence, creativity, memory, and problem-solving abilities. You also lower your risk of developing illnesses such as depression and dementia”, Dr Jebelli says.
It can take three years for your brain to recover from overworking
“When you look at our culture and our working lives, the effects of burnout and overwork on the brain are really profound,” explains Dr Jebelli. “We know that overwork thins the frontal cortex in the same way that ageing does. It literally makes your brain ‘older’.
“It enlarges the amygdala region of your brain, responsible for fight-or-flight, which is why overworked people are anxious and on edge. It shrinks your hippocampus, important for memory, particularly short term.”
Overwork physically “ages” our brain because chronic stress and long hours cause neurons to lose their branch-like structures, known as dendrites. These are essential for communication between brain cells. They are hard to recover and in the long term, their loss leads to cognitive decline. It’s a progressive condition and it can take up to three years of rest and relaxation to put right.
Dr Jebelli points to how 745,000 people a year are dying of overwork, a 29 per cent increase since 2000. Three in five employees report a lack of interest and motivation and energy – a 39 per cent increase since 2019:
“We’re not resting our brains anywhere near as much as we should be. I’m not saying people should not watch their favourite show on Netflix, or be on their phone, or work hard ever again. I’m a hard worker, all I am saying is that we just need to balance that more with rest – and understand that ‘rest’ is your brain doing a lot more.
“Currently, society’s understanding of work and rest is upside down.” Rest, from a business point of view, makes sense too: “Many studies now show that if you give employees more rest, it actually helps the company’s bottom line.” Dr Jebelli pauses, smiling ironically: “although the corporate world is yet to knock on my door and ask for my help.”
Rest as medicine
The brain’s “default network” is our brain’s inbuilt protection against the neurological risks that could harm it. There are different ways of resting that activate the all-important default network. Exercise “in all its forms” is one way, a word not usually synonymous with “rest” but in terms of the default network, Dr Jebelli calls it “active rest”.
“What’s important to remember,” he explains, “is that ‘active rest’ doesn’t just serve as rest for the brain, it also improves the function of our default network.” Any aerobic exercise will stimulate your brain and the default network, as long as you aim for around thirty minutes a day, five days a week.” He adds that a much smaller amount of exercise has anti-anxiety and anti-depression effects, protecting the brain’s neuroplasticity (its ability to adapt and grow).
Dr Jebelli adds: “Active rest in particular does a huge amount for your cardiovascular health. For people with Alzheimer’s and many dementias, there is nearly always some kind of cardiovascular issue as well.”
“Ultimately the crucial thing to remember is that ‘active rest’ – literally just four minutes of gentle exercise every day – lowers your risk of developing a devastating neurological disorder,” he says. “Just as stopping smoking lowers your risk of cancer, embracing active rest lowers your risk of Alzheimer’s disease.”
“In active rest, your brain is releasing a protein called brain-derived neurotrophic factor (BDNF) in the hippocampus, a crucial part of the default network, which has been shown to [help] sprout new synapses and new connections which are really important for brain health. It acts like fertiliser on a garden. All the pharmaceutical companies are really interested in it [as a way] of preventing Alzheimer’s.”
Re-learning how to rest
“The core message of my book is “Do nothing” Dr Jebelli reiterates. Boredom, he says, is vastly underrated by society: “I would argue that true inner self-generated thought is becoming like an endangered species.”
Our 24/7 connectivity means phones constantly ping with texts and emails, leaving no space for intellectual rumination, for play, or for being entirely off-task.
“Our brains haven’t evolved to spend 8 to 12 hours at a time focusing on a cognitively demanding task. We’ve evolved to spend time in nature and yet people still think of ‘rest’ as a kind of luxury.”
Silence, he says, activates the default network, inviting daydreaming and wandering thoughts. In silence, your default network is working creatively and imaginatively in a way that is impossible to achieve with music and podcasts blaring through your headphones. Take the dog for a walk without earphones.
“People always ask me about meditation,” says Dr Jebelli, “because they can think that it’s doing nothing. Meditation is slightly separate but related. It’s focused attention on the present, but what I’m asking people to do is actually much more effortless.”
Being in nature – a park, a wood, a city green square – activates the default network. The rustling of the leaves, for example, and the lapping of waves (if you are by the sea on holiday) are what psychologists call health-giving “soft fascinations”.
In contrast, “hard fascinations” – billboards, train announcements, phones, emails, overbearing bosses – are, explains Dr Jebelli, “all those things which become cognitively draining, not good for your brain”.
A working day, whatever it is, only needs 20 minutes of built-in “rest” through exposure to some kind of greenery. “Twenty minutes seems to be the point at which you get all the neurological and psychological benefits of being in a green space.
“I often get from people “Oh, I don’t have time for 20 minutes a day in the green!” to which I say “Okay, open up your phone for me. Oh look, there’s five hours of screen time right there. Are you not telling me that some of that time could be used on [improving your brain health]?
“My point is that you are going to be more productive in the long run with rest. You are going to perform better and do your best work.” And it might just save your brain too.
