In Blog #47 I wrote about how you could get an extra 2 hours of sleep per week if you moved to the country.

But rather than undergo the logistics of moving house - what if you just went to the country during the day and then returned to your home in the burbs?

The term ‘forest bathing’ has been thrown around more so in the past couple of years. It is said to provide both physical and psychological benefits - including lowering blood pressure and decreasing depression symptoms.

But what about sleep?

What Is Forest Bathing?

When I visited Japan in 2011 with my family, we were blown away by the number of cool things the Japanese invented. I mean, how many families can say that the kids entertained themselves by trying out all 8 buttons on the toilet?

Well, the term Forest Bathing comes from the Japanese phrase - Shinrin-Yoku.

The Japanese Forestry Agency developed this concept when a group of kids were singing “Pass The Dutchie”.

It was intended as a form of nature therapy for people experiencing poor physical or emotional health.

When it comes to a connection between Shinrin-Yoku and sleep, the studies that have been done have been tested on people who are not feeling the best …

Shinrin-Yoku and Sleep Quality

One study was conducted with 9 people diagnosed with gastrointestinal cancer (Kim et al., 2019). They participated in a Forest Bathing program that lasted 6 days and 5 nights - and included:

• 30-min walks that took in the scenery of several species of trees (eg, cypress, cedar, larch)

• 40-min meditation in a hammock suspended between trees

• Aromatherapy massages using oils extracted from the forest

The study found that the participants increased their sleep by 31 min and improved their sleep efficiency (percent of time asleep in bed) from 80% to 89%.

It’s worth noting that sleep was measured by polysomnography (PSG) - which is the most precise way to measure sleep.

As I write this, forest bathing sounds bloody wonderful!

But how did it work?

Was it being in the forest? Was it the meditation practice? Was it the aromatherapy?

It’s hard to tell because it did not have a control group (eg, a group who stayed at home who meditated and received aromatherapy).

But another study did use a control group. They assigned 47 ‘highly stressed’ people to either receive Forest Bathing or Indoor Handicrafts - twice a week for 3 months (Dolling et al., 2019).

And some of you may have guessed it - both groups’ sleep quality improved - suggesting that ‘relaxing activities’ may be the underlying reason for the improvement.

2 Reasons That May Explain Why Shinrin-Yoku Can Help You Sleep

Clearly there is a lot more research that has to be done before we can conclude that Forest Bathing helps your sleep.

But prior to testing an area - it helps to theorise how something can work.

And we can do that based upon work in other areas.

Reason 1 - How You Throw A Rock

For example, there is a lot of emphasise on the importance of getting bright light first thing in the morning. And we certainly know about this because we’ve published clinical trials testing bright light therapy for teenagers.

But what I later learned is that ‘doses’ of bright light during the day may also be helpful for you.

One classic study that bent my mind in this direction improved the sleep of elderly dementia patients - by installing brighter lights in their nursing home.

What this study showed is that not only does bright light help to increase alertness, but doses of it during the day may help our circadian rhythms be more robust. What I mean is that it increases the amplitude of the circadian rhythm - giving it a higher peak during the day.

How does a higher peak of your circadian rhythm help sleep?

Think of it this way. You know when you throw a rock at a shallow angle at water - that it initially skims off the water’s surface? Well, that’s akin to insomnia. But if you throw that rock at a sharper angle, the rock goes straight down beneath the surface. That’s akin to good sleep.

Compared to being indoors, you’re most likely to get brighter light by going outside. And getting a good dose of bright light during the day may help you sleep better at night.

Reason 2 - What Can A Walking Machine Tell Us About Our Sleep?

If you collect all the studies that have tested the link between physical activity and sleep, the consensus is that most forms of exercise mean you will receive better sleep.

Put another way, a sedentary lifestyle is associated with poor sleep quality.

We’ve recently submitted one of our studies to a scientific journal, and we tested this idea.

We had a bunch of teenagers come into our sleep laboratory for 1 week, and they began their day watching TV. The other group of teenagers started their day by getting on a walking machine (some people call this contraption a treadmill).

Whilst I cannot spill the beans yet about what we found, let’s just say that being sedentary wasn’t healthy.

It might take a while before this study gets published (one of the outcomes of COVID is that it’s taking longer to get studies published) - so if you want to know what we found sooner than later - one of our speakers at the WINK Sleep Conference will be spilling the beans…

Conclusion?

Whilst I’m proposing that possible sleep benefits from Shinrin-Yoku may be due to moving outdoors (eg, more light, more physical activity), there could be other mechanisms at play too (eg, being disconnected from technology, air quality, etc).

To be clear, I’m not saying that you shouldn’t Shinrin-Yoku. Like I said, it sounds bloody awesome!

But I’m not convinced yet Forest Bathing is going to be any better than Mountain Bathing or Beach Bathing.

If you do find yourself not sleeping well, perhaps consider whether you need a dose of being outdoors …

• Prof Michael Gradisar