Spoiler: basically, because Good Morning Britain presenter Susanna Reid told me to. Spending 23 minutes outside every day is one of happiness guru Gretchen Rubin’s wellbeing challenges - and it sounds easier than it actually is.

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I interviewed Good Morning Britain breakfast news presenter Susanna Reid last year, a woman whose alarm clock has gone off at 3.45am for two decades. Can you imagine? But Susanna has honed some failsafe coping mechanisms over the years to keep her body and brain on track, despite her unusual work pattern.

“I’ve come to learn that seeing daylight each day is a really important part of my sleep schedule,” she told me. “I try to get outside every day and not just go from an artificially lit house to an artificially lit studio and back again.”

Susanna is a fan of wellbeing whizz Gretchen Rubin, who last year set her followers a challenge – going outdoors every day for 23 minutes, aka Go Outside 23 in 23. “My intention is to do it every day,” said Susanna. Being easily led, I decided to give it a go too.

Remind us - who is Gretchen Rubin?

Rubin’s 2009 book The Happiness Project launched her new career (she was a lawyer) as a global wellbeing expert. Her podcast, Happier, has been downloaded 70m times, she’s sold 3.5m books and Oprah and Dalai Lama are among her fans. She sets a new “fun and manageable” task each year – this year it's a writing challenge, which includes creating a list of 24 things you want to try in 2024. She’s big on incorporating healthy habits into our daily routines: “When we’re trying to create happier lives, we often need to work on our habits; habits are the invisible architecture of everyday life,” she says.

Of the outdoors challenge, she says: “Going outside can include anything from walking to bird watching; from yard work to enjoying your morning coffee on your porch—as long as the door closes behind you, it counts.”

What are the health benefits of going outdoors?

Improved physical health. Assuming you’re moving while you’re outside,  you’ll hit your weekly recommended exercise tally. The NHS says we need 150 minutes of moderate activity per week. If you walk at a decent pace outdoors for 23 minutes per day, seven days per week that’s 161 minutes.

It can help your immune system. Studies show that spending time in nature can help protect against all sorts of illnesses – everything from cardiovascular disease to cancer to depression.

Stress reduction. We all instinctively know a gentle stroll helps us calm down and feel better, and the science is increasingly confirming this – this Japanese research, for example, shows forest bathing reduces stress hormone cortisol.  Neuroscientist Dr Tara Swart says, “Gazing at an uncluttered horizon moves our nervous system from the switched on ‘fright/flight‘ state to the regenerative ‘rest and digest’ state. It also helps us move our way of thinking from detail sensitive to bigger picture.” So we get a different perspective, both literally and metaphorically.

Improved creativity. We tend to have our best ideas when we’re not even trying, when our minds relax. “Walking has been shown to enhance creative thinking, which is exactly what we need when trying to solve problems,” says chartered psychologist Catherine Hallissey. “Other studies have shown it also improves attention.

Increased Vitamin D levels. We get it from sunlight (although in the UK, the sun isn’t strong enough from November to March. The NHS advises we all take a vitamin D supplement during the autumn and winter). Vitamin D is important for keeping bones, teeth and muscles healthy.

Sleep regulation. Susanna is correct – seeing daylight helps regulate our circadian rhythms.

So what’s the link between going outdoors and sleeping better?

Dr Michael Mosley explores this in the Sleep Well: Use Morning Light episode of his excellent health podcast series, Just One Thing (definitely worth subscribing). “A key hormone in the sleep cycle is melatonin – it rises in the evening and plays a role in making us feel sleepy at night. But for most people the internal melatonin cycle isn’t exactly 24 hours,” he says.

“There can be a mismatch between our body clocks and the actual clocks. So we need to reset our internal biological clock every day.” Getting daylight into our eyeballs helps with this. “We have receptors at the back of our eyes that are not used for seeing. Their purpose is to detect light and send signals to a region of the brain called the suprachiasmatic nucleus, one the body’s most important biological clocks. Early daily exposure to daylight has the effect of resetting our central body clock, bringing forward the secretion of the hormone melatonin and helping get you into a regular sleep cycle.” The earlier in the day you see daylight, the better, says Mosley, so ideally head outdoors within two hours of waking.

What happened when I went outside for 23 minutes every day for a week

Image: Molly Scott

If you’ve got a dog that needs regular walks, you’re probably rolling your eyes and thinking, is this even a challenge?  But I don’t have a dog - and I do work full-time, have two children to look after, have a lengthy commute into the city and spend my weekends facilitating the kids' sporting activities rather than, say, merrily skipping through meadows.

So carving out 23 minutes each day is easier said than done, especially in the winter when working regular office hours means you don’t see daylight during the week. I try going for a stroll at 6pm in the dark but Tara Swart says that doesn’t cut it. “The benefits come from being exposed to natural daylight so it would be great to use the lunch break to do this.”

Rubin suggests touching the bark of a tree but I can’t find any as I wander around grimy Hammersmith roundabout, buffeted by human traffic and breathing in exhaust fumes. Instead I head down to the river, “horizon gaze” across the water and feel my shoulders drop.

My verdict

There’s obviously no science behind the 23 minutes tally – it just corresponded with the year 2023 - but I do find it helpful to have that number in mind. It reminds me, for example, that walking to the end of my (tiny) garden or popping to the Pret across the square from Get The Gloss HQ is not enough.

I do find it challenging to get outdoors at lunchtime for this chunk of time – my to-do list is so long, it’s hard to down tools during the day. But I do notice I work far more efficiently – and more creatively - after forcing myself to take the break.

I have less backache too, as my spine spends at least 23 fewer minutes each day being bent into the shape of a chair. I am less sleepy in the afternoon and my mood improves.

I will be continuing the habit – and I know it’ll become much easier as the days lengthen and warm. “I always recommend time outside to my clients, especially time spent in nature, as part of their wellbeing toolkit,” says Catherine Hallissey. Give it a go - you may even bump into Susanna Reid... or the Dalai Lama.