Lack of Sunlight in Autumn and Winter: Vitamin D Deficiency and Seasonal Mood Changes

man reading in office daytime

Sun is life

Sunlight is literally life-giving. Plants need it to grow and animals (including humans) need plants for food and the oxygen they produce. In fact, all life on Earth has adapted to the planet’s 24-hour rotation and the human biological rhythm is also “circadian” (Latin, cicrca diem), meaning it’s about as long as a day, normally entrained to the 24-hour light-dark cycle. Light is the main ‘Zeitgeber’ (German: time giver) that keeps our circadian rhythms on track so that our daily rhythms (i.e. when we eat and sleep) are aligned. Same goes for how we feel; for optimum mood and energy, we all need light to our eyes as bright as a spring morning on a clear day for around 30 minutes a day! And as if this wasn’t enough, we also need it for our body to produce vitamin D naturally, which only really happens when we’re directly exposed to sunlight.

Vitamin D deficiency: how does it manifest and who's at risk?

Because our skin needs UV rays to be able to produce vitamin D in our body, it comes as no surprise that in autumn and winter it is much harder to get enough of the vitamin through sun exposure. In the UK alone, around 10 million people are said to be deficient in vitamin D. If you’re not getting enough vitamin D, this might lead to aching and/or weakened bones, weak muscles, an increased vulnerability to coughs and colds, gut problems and feelings of depression.

Certain people are at higher risk of Vitamin D deficiency and should supplement all year round. These groups include women who are pregnant or breastfeeding, elderly people (aged 65 years and over), people who have little or no exposure to the sun (for example shift workers) and people who have darker skin. Adults who are not part of any of the above “at-risk groups”, should take at least 10 micrograms (mcg) of vitamin D each day during autumn and winter (in accordance with the recommendations issued by Public Health England).

If you’re concerned about your vitamin D status, you can quickly and easily find out your level with an at-home blood spot test or you can talk to your GP about getting tested at your local practice. To read more, check out our low-down on 'the sunshine vitamin' written in collaboration with dietician Nichola Ludlam-Raine.

Sunlight and mood

Recently we talked in detail about the importance of bright light for our mood, mental health and well-being in a work setting, but the findings we presented are relevant to everyone living in the northern hemisphere this time of year.  We've had a pretty good summer in the UK but now days in the sun are merely a distant memory, and it is vital that you don’t ignore the first signs of winter blues and seasonal affective disorder. How have you been lately? Waking up feeling a bit more sluggish, struggling to get going in the morning? Experiencing loss of motivation and decrease in productivity?

If you are battling with seasonal mood changes, the problem may stem from the lack of exposure to sunlight. In autumn and winter - when the days are short and often gloomy - this can be remedied with the help of bright light therapy. The light produced by the light box simulates the sunlight’s intensity. Researchers have proven that bright light makes a difference to the brain chemistry; among others, light is linked to serotonin production (also known as or 5HT), a neurotransmitter in the brain. Research has also shown that serotonin levels increase with exposure to bright light - SSRI drugs such as Prozac have the same effect!

Don't just survive – THRIVE this winter

So what can you do to stay healthy, productive and positive in this grey weather? Create your own sunshine! To help you kick-start your winter wellness routine of vitamin D supplementation and light therapy, we’ve teamed up with Better You to offer a free Vitamin D Oral Spray (containing 100 daily doses!) with any SAD & energy lamp purchased between 21 October – 3 November 2019. That’s over three months' worth of vitamin D supplements, just when you need it the most! Check it out:

Free Vitamin D Oral Spray with any SAD lamp

research sad SAD & energy lights seasonal affective disorder

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