Sunlight and Mood Regulation: How Light Exposure Affects Mental Health
Sunlight is a powerful influence on our daily lives, but to what extent does it impact our mood and mental health?
For many, they simply feel happier in summer and noticeably bluer in winter. For others, the distinction isn’t so obvious. This article will explore the ways that light (and the absence of light) impacts health, bodily functions and mood. Plus, you’ll learn how sunlight and mental health conditions can interlink.
This article will also explain exactly what our bodies do with sunlight and the lifestyle changes you can make to see improvements in your mental well-being by discussing:
- Quick facts about mental health and daylight exposure
- The different ways our bodies respond to light
- How sunlight can impact mental health and sleep
- Why you might be getting lower levels of light exposure
- FAQs about improving mental health with light
Quick Facts About Sunlight and Mental Health
Before we do a deep dive into how sunlight and mental health are connected, here are some quick and intriguing facts to know:
- People who have been hospitalized for depression recover more quickly in sunny rooms.[1]
- Long-term exposure to moderate levels of UVB (Ultraviolet B – a ray coming from sunlight) can inhibit the development of depression.[2]
- People living in areas with higher and longer exposure to sunlight experience fewer depression symptoms.[2]
- A lack of sunlight exposure may increase the risk of hospital admission for people with schizophrenia.[2]
These extraordinary findings suggest a strong link between light and well-being. But what’s really going on?
How Do Our Bodies Respond to Light?
Light plays many roles in human health and functioning. It facilitates vision, regulates sleep and hormones, and affects mood.[1] Exposing the skin to sunlight may reduce our blood pressure, and cut the risk of heart attack and stroke. It can even provide pain relief by increasing the production of endorphins – one of our body’s ‘feel-good’ chemicals.[3],[4]
These occur because of the way human bodies absorb and convert light. In summary, our bodies:[1]
- Absorb light through our eyes, which sends signals to our brain’s internal ‘clock’ and enables vision
- Trigger the release of serotonin and other neurotransmitters and hormones involved with sleep, mood, stress, hunger, and body temperature
- Convert light into vitamin D, helping with brain function and the regulation of neurochemicals like dopamine
As a result, our whole physical, mental, and emotional experience of being alive is impacted by light. Sunlight’s effect on serotonin production, the sleep-wake cycle, and its role in regulating brain function all play a part in shaping someone’s mental health.
Sunlight and Mental Health
A lack of sunlight can have varying effects on our mental health. Some people will experience low mood, feel a worsening of their pre-existing symptoms, or develop seasonal affective disorder (SAD) when winter comes around.
Plus, since light can impact sleep, a combination of low light exposure and poor sleep can induce or worsen mood symptoms. Let’s explore these now:
SAD and Winter Depression
Seasonal affective disorder (SAD) is a type of depression that occurs during winter. Although its exact cause is unknown, research points to sunlight as a significant contributor because SAD symptoms often arise for many as we move into the winter months.[5]
SAD symptoms for adults are very similar to the signs of depression depression: feeling hopeless or worthless, struggling with sleep, losing interest in activities you used to enjoy, and changes in your appetite. You might withdraw socially or experience lower libido.[5]
SAD occurs because of how light interacts with hormones and neurochemicals in your brain. A lack of light causes your brain to release:[6]
- Less serotonin (the feel-good neurochemical)
- More melatonin (the hormone that helps you sleep)
These changes can trigger feelings of lethargy, sadness, and eventually induce SAD.
Light, Sleep, and Mental Health
Getting good quality sleep is always advised in conversations about mental health, but the importance of light doesn’t tend to be emphasized as much as it should be.
We all have a circadian rhythm, which involves the sleep-wake cycle, the production of certain hormones, and the regulation of body temperature throughout the day. Light has a big role in regulating these processes, which can then affect how well you sleep. For example, nighttime light exposure can induce ‘phase-shifts’, which is when your body’s internal clock is moved forward.[1]
Our circadian rhythms might also be negatively impacted by the light pollution that’s common in urban areas and that people may be exposed to through rotating shift work. These factors could be a risk factor for developing metabolic and hormonal disorders.[1]
Anxiety and Mood Disorders
Though experts don’t totally understand why, it’s well-established that some mental health conditions undergo seasonal changes throughout the year.[7]
Separate from SAD, seasonal fluctuations in symptoms can occur for many psychiatric diagnoses, including bipolar disorder, major depressive disorder, and a range of anxiety disorders.[7]
The most likely reason for these seasonal changes is sunlight’s impact on serotonin. Research finds our serotonin levels are at their lowest in late spring and highest in late summer and fall.[7]
So, through changing sleep quality and the availability of neurotransmitters like serotonin, light can have a significant impact on mood regulation.[8]
Why You Might Have Low Sunlight Exposure
Human physiological functioning is optimal when our circadian rhythms are in sync with the day-night cycle. However, our modern lives are marked by darker days and brighter nights.[9]
Because of where we live and how we spend our time, many of us are at risk of being exposed to less sunlight than is ideal for good health. Namely, in western developed countries, people are more likely to spend a great deal of time indoors and be limited to time outdoors in the summer months.[1]
Furthermore, studies find that sunlight exposure in rural areas has a more evident impact on mood than sunlight in urban environments.[1] This suggests that spending time in natural environments is important for mood, and highlights that there are many factors at play when it comes to mood regulation – not just sunlight.
In summary, you might be getting suboptimal levels of light if you:
- Live in a city
- Spend most of your time indoors
- Live in a place that has short days throughout the winter months
- Do rotating shift work
Fortunately, there are many things you can do to improve your exposure to light, which we’ll explore in the following FAQs.
Common Questions on Sunlight and Mental Health
Below, we explore some of the most commonly asked questions when it comes to the relationship between sunlight and mental health.
Can Mental Health Be Treated with Light?
Light therapy (also known as phototherapy and bright light therapy) provides therapeutic effects through exposure to superficial light.[1] If you’re prescribed light therapy, you’ll be given a light box to sit close to every morning for about 30 minutes.[10]
As a seasonal affective disorder treatment, light therapy is a non-invasive option with little to no side effects. It can also be used for other mental health diagnoses. For example[11]
- Light therapy is a second-line treatment for non-seasonal depression, though results take longer and are more effective when combined with SSRIs.
- It could also be a therapeutic option for perinatal depression and premenstrual dysphoric disorder.
As well as depression, light therapy has been found to be an effective add-on to other therapies for conditions such as:[11]
- Attention deficit hyperactivity disorder (ADHD)
- Borderline personality disorder (BPD)
- Schizophrenia
- Anorexia and bulimia nervosa
Light therapy for depression might involve a prescribed, hour-long, morning walk, instead of an artificial light box. This has been shown to be similarly effective but, of course, isn’t a reliable option for those living through dark winter days.[11]
Are Vitamin D Supplements Enough?
Taking vitamin D supplements is a popular way to support mood, immune function, and bone health throughout the year. Many wonder if taking vitamin D for mood, instead of natural sunlight, is enough and whether sunlight exposure is essential for mental health.
Vitamin D supplements are extremely important for people with a deficiency and can be a helpful addition to getting the vitamin from food and sunlight in others.[12]
However, research by the University of Edinburgh found that when the skin is exposed to sunlight, nitric oxide is produced, which can help reduce blood pressure.[4] This process is separate from the body’s production of vitamin D, which happens after sunshine exposure. This suggests that skin exposure is important and that vitamin D supplements cannot compensate for a lack of sunlight for every health outcome.[4]
Furthermore, research suggests that our skin might play a significant role in the production of serotonin, alongside what we know about its stimulation via the eyes.[7] This may explain humanity’s enjoyment of sunbathing and highlight the importance of getting sunlight to our skin.[7]
How Much Sunlight Do I Need?
There is a great deal of disagreement and misinformation about sunlight and vitamin D, so it can be difficult to know what to listen to. However, sunlight is unarguably the best way to get vitamin D: It’s free, and our bodies can self-regulate the amount of vitamin D it produces, making toxicity highly improbable.[12]
Those wanting to treat their depression naturally with sunlight may be worried about balancing this wish with skin cancer concerns. The bottom line is that you don’t need to be in the sun for long to get the brain benefits of sunlight. After no more than 30 minutes, you should apply sunscreen and wear clothing for protection.[12]
For those who are deficient in vitamin D, the recommended daily dose is 1,000 IUs (international units). However, for those who just want to maintain good levels of vitamin D, 600-800 IUs are sufficient.[13],[12]
Since the sun’s light is stronger in spring and summer, the amount of time you should spend in the sun varies throughout the year. For optimum doses of vitamin D, it’s estimated that 10-20 minutes per day is enough in spring and summer, but that almost two hours are needed in winter.[13]
These figures are rough because the recommendations depend on the country you live in, the time of day, your skin type, and how much skin is exposed to the sun. Furthermore, our ability to produce vitamin D from sun exposure decreases with age.[13]
As well as through sunlight and supplements, you can also get vitamin D from food. Many cereals and plant-based milks are fortified with vitamin D, while many types of fish are naturally high in it.[14]
How Else Can I Regulate My Mood Naturally?
For those who prefer natural methods, there is a range of lifestyle changes you could consider. We’ve written about the following natural methods of mood regulation:
Mission Connection: Personalizing Your Mental Health Care
In the spirit of driving out the darkness and letting the light in, here at Mission Connection, we’d like to welcome you to explore our therapy options. We operate from multiple facilities across the US, and offer online therapy.
We treat a wide range of mental health conditions, personalizing the treatment of each person who seeks our support. If you’re someone who wants a natural approach, we can easily incorporate that into your treatment plan.
Browse our therapies or take a self-test today to learn more.
