Have you ever wondered why a brisk walk around the park at lunchtime helps to clear your head, or why you feel especially calm after a weekend break in the countryside? The answer is quite simple: being surrounded by nature has a calming effect.

Several scientific studies have highlighted a link between nature immersion and improved health and wellbeing – one 2021 study (conducted during Covid-19) demonstrated that experiencing ‘nearby nature’ (visiting your local park, for example) can help prevent poor mental health during a stressful time. The study also found that self-esteem, life satisfaction and subjective happiness were all positively related to the frequency of green space use and green views through windows at home, while feelings of loneliness, depression and anxiety were reduced.

With that in mind, it’s no wonder that activities like hiking, forest bathing and wild swimming are rising in popularity – in an increasingly fast-paced, digital world, we’re physiologically craving a connection to the natural world.

And yet, in our busy lives, it can be so easy to forget how effective a tonic nature is, and sometimes we just need a gentle reminder to get outside. This is where the 20-5-3 rule can be helpful.

The rule was coined by Dr Rachel Hopman, a professor of psychology at the University of Utah, who took Tanya Denckla-Cobb’s ‘nature pyramid’ (a concept based on the food pyramid to remind us to incorporate nature into our lives on a daily, weekly, monthly and annual basis) and simplified it into what she called the 20-5-3 rule.

The 20-5-3 rule entails spending 20 minutes in nearby green spaces three times a week, five hours a month in a semi-wild environment and three days a year in complete off-grid wilderness.

Thanks to its clear-cut terms, the 20-5-3 rule has been dubbed ‘nature’s prescription’ – but is it doctor-recommended?

Depending on your lifestyle and how urban an environment you live in, you might find that you already manage to tick off parts of the rule. Perhaps you make sure to walk through your local park on your way to work each morning or you often enjoy a Saturday rambling in the countryside. Perhaps your idea of a good time is turning your phone off and heading to an unplugged campsite for the whole weekend. If that’s you, well done. However, this trend is all about getting regular hits of nature at all the different levels.

Dr Tamsin Lewis, a longevity doctor and wellbeing expert at wellgevity.com, says the rule is a helpful starting point for those looking to reconnect with nature. “It’s not a magic fix, but it reflects a growing body of research showing how natural environments support nervous system regulation, reduce inflammation and improve mood, sleep and metabolic health,” she says.

“It provides a clear, actionable structure – something that can be helpful in a world overloaded with wellness advice,” Dr Lewis continues. “For people experiencing burnout, emotional dysregulation or nervous system overload, it gives a scaffold to anchor back into their biology using the outdoors. Sometimes having that prompt to schedule nature time can open the door to deeper awareness and lifestyle change.”

Dr Lewis says the 20-5-3 rule can be particularly useful for people with high cognitive loads or stress, or those who benefit from frameworks to create boundaries with work and tech. “For patients navigating long Covid, hormonal shifts, perimenopause or chronic stress, structured nature exposure can help regulate the autonomic nervous system and create space for recovery,” she explains. “It also works well for urban dwellers, especially if it inspires them to seek out new environments, even if semi-wild.”

However, Dr Sarah Jane Khalid, a psychologist from Doctify, says that everyone can benefit from the 20-5-3 rule. “But those who would particularly benefit include anyone who struggles with health, has emotional or mental difficulties, and the young and old to help with strengthening their immunity,” says Dr Khalid.

Nature exposure is increasingly being found to support almost every system and function in the body. It lowers cortisol, improves heart rate variability, boosts immune function and supports better sleep, metabolic regulation and mood.

“From a neurological perspective, it calms the amygdala (linked to fear and hypervigilance), enhances parasympathetic tone and encourages activity in brain regions associated with creativity, reflection and emotional regulation,” says Dr Lewis.

Dr Khalid says there’s a wealth of evidence for associations between nature exposure and improved cognitive function, brain activity, blood pressure, mental health, physical activity and sleep.

“There’s also a growing number of studies that show spending time in nature has positive benefits on mental health, and that even brief contact with nature promotes positive emotional states,” says Dr Khalid.

Interestingly, there’s growing research connecting soil microbes, biodiversity and outdoor air to the gut-brain health axis, which means time spent in nature can help regulate inflammation, immunity and even neurotransmitter production. One 2007 study found that forest bathing was positively associated with stronger immune function.

There’s even some evidence that the colour green, which is so dominant in nature, can reduce pain. “One fascinating recent study showed that wearing green-tinted glasses reduced pain intensity in people with fibromyalgia,” says Dr Lewis. “While it may sound fringe, it underscores a deeper point: our sensory systems are profoundly attuned to natural stimuli.”

The structure of the 20-5-3 rule promotes the idea that it’s not just about spending as much time in nature as possible, but that there are different degrees of wilderness that we should be hitting. But isn’t all nature the same? Is there really a difference between your local park and the Brecon Beacons?

“Yes, and it’s about depth and duration,” says Dr Lewis. “Local green spaces offer microdoses of restoration that are powerful for day-to-day recalibration. Just 10–20 minutes in nature can reduce sympathetic nervous system activity and promote calm. This consistency matters, especially in our overstimulated environments.”

However, Dr Lewis stresses that deeper immersion in wilderness offers something different: a chance to fully reset the system. “Away from artificial light, digital input and environmental noise, the brain and body downshift into slower rhythms. These immersive experiences can catalyse more profound emotional shifts, creativity and a deeper sense of connection – to self and surroundings. It’s the difference between topping up and truly rebooting the nervous system.”

Dr Khalid agrees there’s a difference between an urban pocket of green space and total wilderness. “I honestly believe there’s a difference given how much more greenery and wildlife you find in more rural and remote locations,” she says. “Diversity is an important factor to consider when thinking about spending time in nature. Experiencing different smells from a variety of flowers, plants and trees is better for strengthening your microbiome, while taking in new information from different sights, sounds and vibrations is good for cognitive function.”

As is often the case, it’s worth taking trends like the 20-5-3 rule with a pinch of salt. Getting out into the total wilderness for three straight days might not be viable, logical or affordable for you, so don’t beat yourself up about it if you can’t do it.

“The rule isn’t perfect, but it’s a nudge in the right direction,” says Dr Lewis. “That’s why I see the 20-5-3 rule not as a rigid prescription, but as a useful cue to rewild the body and mind. For many, especially those dealing with burnout, mood dysregulation or low-grade chronic inflammation, these consistent doses of nature can act like a gentle reset.”

Health isn’t about ticking boxes, and what works for one person might not work for another. “The rule risks being overly rigid and doesn’t account for the complexity of individual needs, access to green space or how someone’s body and mind responds to nature,” says Dr Lewis. “For some, a short daily connection to a familiar outdoor space is far more impactful than a weekend away once a year. Wellbeing is dynamic. One person’s reset might be a 10-minute forest walk, while another’s might require three days off-grid to truly shift their physiology.”

Dr Khalid says that the most important thing to take from the 20-5-3 rule is to get out of our homes as much as possible. “We were never meant to live in single occupancy households, so whatever time you can afford, intentional commitments would show immense change to your wellbeing in general.”

If you enjoy structure, then something like the 20-5-3 rule might be what you need to immerse yourself more in nature. However, if the 20-5-3 rule doesn’t sound like it will fit into your lifestyle, Dr Lewis suggests building a ‘nature rhythm’ instead.

“Daily exposure – morning sunlight, walking barefoot on grass, a walk in a tree-lined street – can be incredibly effective when done with presence,” recommends Dr Lewis. “Layer in seasonal immersion, such as cold water swims, wild walks or even gardening, and you create an ecosystem of support for your biology. Start where you are, reconnect regularly and go deeper when you can. Nature meets us in different ways – what matters is that we keep returning to it.”

Images: Getty