Low on energy? A new understanding of rest could help revitalise you
SOURCE:New Scientist
There is a state of relaxation that few of us spend much time in, but which comes with profound well-being benefits. With healthier ageing, reduced risk of disease and feeling more energised all on offer, here's how to get there
There is a state of relaxation that few of us spend much time in, but which comes with profound well-being benefits. With healthier ageing, reduced risk of disease and feeling more energised all on offer, here's how to get there
It happens every new year. Party time is over, and it is time to brace yourself for the predictable onslaught of health advice. Most of it will involve doing more of something that you already know is good for you. More exercise. More cooking from scratch. More wholesome, mindful hobbies. It is no wonder so many of us fall off the wellness wagon before the month is out. No matter how sage the advice, who has the time and energy to do more of anything? If this sounds familiar, it might come as good news that scientists have come up with a more appealing alternative – one that still promises to increase your chances of staying healthy for longer, but involves doing less, not more.
Or, more precisely, that involves perfecting the art of doing, physiologically speaking, as little as possible. This unusual, yet deeply effective, twist on the New Year’s resolution hinges on mastering a physiological state that many of us spend few of our waking hours in. It is called deep rest – a way of being in which signals between the body and brain align on one fundamental fact: that all is well and there is absolutely nothing to worry about.
In essence, it is the polar opposite of stress. Deep rest is a state where the body can take a break from fighting and fleeing, instead regrouping and catching up with some much-needed maintenance and repair. And while it might take some trial and error to find your personal off switch, the evidence is accumulating that the payoffs could be huge: healthier ageing, reduced risk of disease and more energy to spend on something other than maintaining an ambient panic response.
Alexandra Crosswell is a psychologist at the University of California, San Francisco, who, along with a group of her colleagues, proposed the idea of deep rest in early 2024. She is aware the term may sound familiar to some. Andrew Huberman, a Stanford neuroscientist turned wellness influencer, has widely promoted what he calls “non-sleep deep rest” on his podcast and social media channels. But, says Crosswell, the two aren’t quite the same. “The difference between how we define deep rest and how Huberman describes non-sleep deep rest is that his is a relaxation practice and ours is a psycho-physiological state,” says Crosswell. “Deep rest is beyond relaxation – it’s a coordinated shift of the whole nervous, endocrine and immune system into an overall state of safety signalling.”
Stressing out
It is a truth, universally acknowledged, that if one thing could transform human health, it would be an antidote to stress. Problematic stress is a centuries-old issue that people have been complaining about since at least the industrial revolution. The things that generation struggled with – the cost of living, the pressures of work and family and an unsettling change in the pace of life – are still as relevant today as they were then. What’s new is that these very human concerns are layered on top of an underlying current of unease fuelled by 24-hour access to awareness of global crises, many of which seem frighteningly out of our control. There are signs that all of this is taking a serious toll.
According to a 2022 survey of over 3000 US adults, more than a quarter of respondents said stress made it difficult to function in daily life. Meanwhile, chronic stress has been linked to soaring rates of everything from depression and anxiety to cardiovascular disease,high blood pressure, infectious diseases and some cancers. It is a major factor in the epidemic of tiredness and fatigue and is linked to accelerated ageing and an increased risk of all-cause mortality from middle age onwards. Yet despite an overwhelming consensus that too much stress is bad for our health, it has proved difficult to pin down exactly why, which has made it difficult to know how to go about fixing the problem. The big picture is clear enough and, arguably, pretty obvious.
“ While a stress response is on the go, the body takes a break from less urgent processes like digestion, reproduction, maintenance and repair “
Stress is draining because, whether the threat is physical or psychological, mounting a stress response requires a huge investment of the body’s resources. In experiments, a short bout of psychological stress increased volunteers’ energy expenditure by up to 67 per cent above their resting metabolic rate. Other studies suggest that about a third of this energy is spent on fuelling the rise in heart rate, with the rest accounted for by the cost of producing stress hormones and inflammation. Once the stress hormones are circulating in the body, they have knock-on effects on the cell’s metabolism.
The stresses of modern life leave many of us feeling depleted
Corbis via Getty Images
Human cells that are chronically exposed to stress hormones in the lab have been found to burn through energy 60 per cent faster, age faster and die younger. The whole process gobbles up so much energy that, while an active stress response is on the go, the body takes a break from less urgent processes like digestion, reproduction, maintenance and repair. The stress response is an example of a process called allostasis, or “stability through change”. Allostasis is different from the more familiar process of homeostasis, which describes how we regain balance after one or more biological processes have been knocked off course by environmental change.
In allostasis, though, the adjustments don’t happen after change, but in advance, based on the brain’s predictions about what is likely to happen next (like identifying a possible incoming threat) and how best to adapt (like by flooding your system with hormones as part of the fight or flight response.) “Your brain is predictively regulating your body,” says Lisa Feldman Barrett, a neuroscientist at Northeastern University in Boston. “Your body is [then] sending signals back to your brain about the sensory conditions of the body and the sensory consequences of allostasis.”
How the brain regulates the body
Recently, a group of neuroscientists, including Feldman Barrett, have argued that allostasis isn’t just a side project for the brain; rather, it is its main function and number one priority. In this view, thinking, feeling and action all work in service of allostasis, helping the brain reach its goals by motivating us to do whatever is necessary to balance the books and stay alive. This new view of the brain puts a spin on the challenge of tackling the epidemic of stress, says Karen Quigley, also at Northeastern University, who, along with her colleague Feldman Barrett, proposed the idea in a 2025 paper in the journal Neuron.
“If you start from the biology and try to understand this important and critical role for a brain managing its energy budget, then you start to think about concepts like stress slightly differently,” says Quigley. Thinking of toxic stress as allostasis gone awry helps explain why the expense of chronic or repeated stress takes its toll on our health. Allostatic states, like stress, are supposed to be temporary.
In short bursts, the investment is worthwhile when you need to run, fight or think your way out of a crisis. But given that most modern threats aren’t actually likely to lead to your demise, much of the time, the investment is metabolic overkill. And given that daily hassles are a part of life – a survey of US adults reported an average of three or more stressful events a day – there is often little time to recover before the next thing hits the fan. The result is tension, fatigue and an increased risk of poor health, as the body continues to sideline maintenance and repair in a misguided attempt to be ready for anything.
Your internal ‘off switch’
Ironically, there is some evidence that constantly being in “a little bit on” state makes the body less efficient at responding to acute stress, so when we actually need our fight or flight system, it’s as worn out as we are. In better news, the fact that allostatic states are temporary by nature raises the possibility that if we can find the right bodily switch, we can change the signal, and the accompanying allostatic state, to one where all is well and biological bankruptcy isn’t an immediate concern.
“It may be that you can create a ‘system reset’ partly by enhancing signals that current resources are sufficient,” says Quigley. This is where the idea of deep rest comes in. Crosswell and her colleagues set out to explore why contemplative practices like prayer, chanting, meditation, yoga and qigong (a practice involving flowing, coordinated movements) have positive effects on physical health and mental well-being, reducing self-reported levels of stress and improving markers of physical health such as blood pressure and inflammation.
Bringing together a team of researchers spanning neuroscience, physiology and cellular metabolism, the idea was to identify the special sauce in these practices. They concluded that the beneficial effects of contemplative practices come from the way they put a spanner in the physiology of the stress response. “These practices put the organism in a state of lower energy demand,” says Martin Picard, a mitochondrial psychobiologist at Columbia University who collaborated with Crosswell on the research. When the brain gets the memo, he says, it starts to be generous with its resources. “Instead of wasting your energy making cortisol and speeding up your heart rate, you have this energy pool that’s available for restoration,” he says. Studies suggest that contemplative practices do indeed reduce energy consumption.
Mindful practices like qigong can help you enter a state of deep rest
VCG/VCG via Getty Images
Research dating back to the 1970s found that during transcendental meditation, metabolic rate dropped by 40 per cent compared with when the same volunteers were sitting quietly without meditating. Studies of regular yoga practitioners have also found that they consume up to 15 per cent less energy at rest than non-practitioners and have lower resting heart rate and blood pressure and lower levels of circulating stress hormones.
As to what exact mechanism is behind the effect, Crosswell and her colleagues speculate that one thing these interventions have in common is – by accident or design – that they tend to involve slow, deep breathing. Deep breathing, particularly at or around 6 breaths per minute, activates stretch-sensitive sensors in the chest, which activate parasympathetic activity in the vagus nerve (see “Breathing your way to deep rest“, below). The parasympathetic nervous system controls the so-called rest-and-digest response, which is the polar opposite of fight or flight. When parasympathetic activity is high, heart rate, blood pressure and other signs of arousal are low, and the body gets on with all the internal housekeeping that it has been keeping on hold.
“ With prayer and mindfulness and other deep rest practices, you’re moving your mind away from worrying about the future into this present moment “
The shift to parasympathetic dominance, combined with the meditative element of these practices, might be enough to persuade the brain that there is no longer any threat, and to stand down, says Crosswell. “With prayer and mindfulness and other deep rest practices, you’re moving your mind away from worrying about the future into this present moment,” she says. Assuming that the here and now feels safe, this adds a second positive signal for the brain to factor into its budgeting – what Crosswell calls a “present moment sufficiency mindset” or “that right now, I have all the energy I need”.
A woman rests in a flotation tank, another way of sinking into a state of profound rest
nya Semenoff/The Denver Post via Getty Images)
A 2025 study on using a mindfulness intervention seems to back up this idea that deep rest makes a measurable difference. Those who did 10 sessions of an hour-long mindful breathing and stretching-based practice had higher levels of healthy metabolic markers in the blood and lower levels of those associated with disease risk. A comparison group whose participants underwent relaxation training showed no such changes. This precise prescription wouldn’t work for everyone, however; for some, meditation might evoke a stress response, for example. Different options include paced breathing, particularly hitting those apparently crucial 6 breaths per minute, or simply spending time with a loved one who makes you feel safe.
As social creatures, our brains are wired to factor in how much support we have to deal with life’s ups and downs. Its power as an antidote to stress may even explain why close, supportive relationships are linked to better health and longer lifespan, says Quigley. “Humans are really critical allostatic supports for one another,” she says. “Social support is an important allostatic regulator.”
Social connection
A good way to super-charge social support – or to mimic it if you don’t happen to have a loved one to hand – involves activating skin-based sensory nerves that are thought to have evolved to solidify social bonds. Known as C-tactile afferent fibres, these fire most enthusiastically when stroked slowly and gently at close to body temperature. Experiments into the effects of this “affective touch” have shown that it not only feels pleasant and calming to people of all ages, but it also leads to a drop in heart rate and other markers of parasympathetic activity, even when applied during a stressful experience. Research suggests that a soft-bristled brush stimulates these nerves almost as well as a loving caress from an actual human. A team of researchers at Cornell University in New York state are even trialling a wearable device that has shown promise in early tests as a stress-buster.
But the paramount message, says Crosswell, is that there is no single route to deep rest. Some people find meditation more stressful than calming, while others find affective touch ticklish or rage-inducing. What’s important is to seek out something that makes you feel warm, safe and calm from the inside. The ultimate state of deep rest, of course, is sleep, a time when the energy savings of being still and breathing more deeply allow the body to flush out the brain and make repairs to the body. It is possible that, for anyone short on sleep, adding deep rest to waking hours could help make up the shortfall.
As for how much you need to neutralise the effects of stress, the answer is: it varies. “I wish I could say how many minutes is enough,” says Crosswell. Even so, with growing evidence that deep rest is a state worth making time for, the best advice right now is to find where you feel safe and spend as much time in it as possible, basking in the knowledge that you are investing in your long-term health.
Smartphones and watches, with their constant flurry of updates and notifications, seem like the antithesis of a calm, stress-free existence. But for anyone keen to find their own deep rest state, they do have their uses.
One marker of stress regulation that comes as standard in most smart watches is heart rate variability (HRV) – a measure of the tiny variations of the time between successive heartbeats that is used as a marker of overall physiological stress, and of how efficiently the body is managing its resources. Different devices use slightly different measures, and what counts as healthy varies by age, but a higher HRV is generally considered healthier. An HRV below 25 millisends (ms), for example, has been linked to a greater risk of cardiovascular disease and depression.
A tried and tested way to boost HRV is via resonance breathing biofeedback, in which slow breathing at around 6 breaths per minute causes two of the body’s key heart-rate regulating reflexes to synchronise so that each boosts the activity of the other. The net result is a boost to the parasympathetic (rest and digest) arm of the nervous system. Some research suggests that when practised regularly, HRV biofeedback trains the body to recover more efficiently after stress.
While HRV biofeedback works best when both blood pressure and heart rate are measured in the lab, apps exist that offer breathing exercises based on real-time measurements of HRV. I spent a four-week period self-experimenting using one such app, combined with a chest-mounted heart rate monitor. Week one was spent logging my baseline average HRV. During week two, I did 20 minutes of resonance breathing biofeedback a day, and in the third week, I took a break from daily training. For the final week, I returned to training.
The results were clear: during the biofeedback weeks, my average daily HRV, measured on my Apple Watch, came in at between 55 and 60 ms (at the healthy end of normal for my age), more than 10 ms above the just-about-healthy baseline I established in week one. The effects seemed to spill over during my week off, with my average HRV staying higher than average, before returning to the high 50s in my final week of training.
This was encouraging, but the training is quite time-consuming. So I was keen to try an even easier alternative. According to its website, the Nurosym vagus nerve stimulator has been shown to significantly increase HRV and improve other markers of stress. The device attaches via a clip to the hard flap of cartilage at the front of the ear, where a branch of the vagus nerve runs close to the surface. I used the device (lent to me by the company) three times, for up to 20 minutes, at the same time of day as I had previously done my breathing practice.
The results were… mixed. The stimulation either led to no change in HRV, a slight decrease (55 ms before, 48 ms after), or a very slight increase (45 ms before, 48 ms during, 51 ms after). Confused, I contacted Julian Koenig, a psychobiologist and member of the international consensus group on transcranial vagus nerve stimulation research.
He points out that my results are about as consistent as what has been found in various studies on the subject. Yet while results vary, the study the company refers to on its website, published in 2022, is something of an outlier in the field in showing an increase in HRV with stimulation.
“That’s why we did [a] meta-analysis,” says Koenig. So far, he says, the published results of the consensus group’s ongoing “live” meta-analysis have shown “no effects on heart rate or HRV” during short-term stimulation. And while there is still much to learn about what, if anything, these devices can do for health, he says that, for now, “if the goal is to increase HRV, deep breathing is one of the best and cheapest options”.
