Only a crazy person would tell his fellow Australians to stand for hours in the sunshine. What with melanomas and all that.

So, for the sake of being responsible, let me say this, please: for most of the time you spend outdoors, slip slop slap your little hearts out. Especially in the warmer months.

On the other hand, we need a good dose of sunlight.

And as a particularly grey old winter hits the home straight, at least for half the country, the sky has been exhibiting an on and off burst of golden splendour. A friendly glint if you will.

One thing I’ve noticed on thise gilded occasions, whilst walking my ridiculous 20,000 steps a day (it’s a foot fetish, okay?) the people I pass in the street are cheerier, friendlier.

And they’re not all over compensating for walking around with their dogs criminally off their leashes.

A touch of the sun – spring having almost sprung – is an immediate cheerer-upper.

Why you feel chippier, maybe frisky

Being touched up by the sun increases your serotonin levels – serotonin being a neurotransmitter that also acts like a hormone. It’s commonly described as a “feel-good” drug.

How does this happen? When sunlight enters your eyes, it stimulates the parts of your retina that cue your brain to produce serotonin.

Serotonin is thought to play a role in regulating mood, emotions, appetite, and digestion. And better sleep.

Being out in the sunshine can make you cuddly wuddly. Photo: Getty

On the mood front, it gets you feeling happy and ready to rock… with life. It also plays a role – in tandem with the neurotransmitter dopamine – in your desire for sex.

Insufficient serotonin – from poor exposure to sunlight – is implicated in depression, anxiety, mania and Seasonal Affective Disorder. Or just feeling blue. And wintry.

Serotonin you soak up from the sun’s rays does more than boost your mood – it might also help you get more restful sleep at night. Working in tandem with serotonin is melatonin, a chemical in your brain that lulls you into slumber and one that sun also helps your body produce.

Sunlight lowers your blood pressure?

In 2014, UK researchers demonstrated that sunlight alters levels of the small messenger molecule, nitric oxide (NO) in the skin and blood, reducing blood pressure.

Martin Feelisch, Professor of Experimental Medicine and Integrative Biology at the University of Southampton, explained:

“NO along with its breakdown products, known to be abundant in skin, is involved in the regulation of blood pressure.

“When exposed to sunlight, small amounts of NO are transferred from the skin to the circulation, lowering blood vessel tone; as blood pressure drops, so does the risk of heart attack and stroke.”

Follow-up research

In 2020, Professor Feelisch and his team published a huge study that examined blood pressure readings from more than 342,000 patients at nearly 2200 clinics over three years, starting in January 2011. More than a third of the patients were African American.

According to a report from the American Heart Association, “blood pressure readings were averaged by month, then matched with reports on outdoor temperature and ultraviolet radiation, which also were averaged into monthly readings”.

Researchers adjusted for variables such as the subjects’ sex, age and body mass index.

When the numbers from nearly 46 million blood pressure readings were crunched, the researchers “found exposure to UV sunlight was associated with lower systolic blood pressure (the first number in a blood pressure reading) regardless of the temperature”.

A string of studies have since confirmed the association – and the observation that blood pressure tends to be higher in winter and lower in summer has been understood for years.

One theory was that low temperatures cause blood vessels to temporarily narrow. Blood pressure goes up because more pressure is needed to force blood through narrowed veins and arteries.

It’s accepted that temperature does play a role. But so does sunlight.

Oh yeah, and vitamin D

Vitamin D. It’s the best known benefit of sunlight, and a tricky one. You need vitamin D to facilitate the absorption of calcium, and to modulate the immune/inflammatory response.

About one in four Australians have a vitamin D deficiency – which lead to a loss of bone density, which can contribute to osteoporosis and fractures (broken bones).

The tricky part is best explained by the Cancer Council:

“The sun’s ultraviolet (UV) radiation is both the major cause of skin cancer and the best source of vitamin D.”

For a detailed piece of advice from the Cancer Council about how best to solve this paradox, see here.

The short version:

“A few minutes of mid-morning or mid-afternoon sun exposure to arms and hands on most days of the week should be sufficient to maintain adequate Vitamin D.”