Seasonal Affective Disorder (SAD) and Red Light Therapy

Seasonal Affective Disorder (SAD) and Red Light Therapy

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When it comes to transitioning into a new season, it’s not uncommon to experience what is known as Seasonal Affective Disorder (SAD). In this article, we provide an overview of SAD, how sunlight impacts season change, and how the use of light therapy can be a solution during months when SAD is most common.

What is SAD?

SAD is categorized as a change in mood that coincides directly with season change. Most people report experiencing symptoms of SAD throughout the fall and winter months, and notice more relief during spring and summer. These symptoms can vary greatly, with the most common being a decrease in overall energy that occurs at a similar time every year. [1] So why does Seasonal Affective Disorder happen? While scientists do not fully understand the cause, research indicates that SAD is linked to a lack of light exposure, specifically sunlight. This is why symptoms often start in the fall when the days become shorter and sunlight loses intensity. Due to the sun’s position, this can especially be the case when living in more northern latitudes, compared to those living further south.

How Sunlight Impacts Us 

So how does the position of the sun contribute to someone experiencing SAD? Well, it all depends on the ‘sun angle’, the angle at which the sun strikes earth. [2] While this seems fairly straightforward, the sun angle plays a significant part in determining the yearly seasons, as well as impacting the amount of heat energy the earth receives throughout the year. This varies by location due to the earth always being tilted at a 23.5° angle, while continuously orbiting around the sun. [3]  As expected, cooler weather typically brings more saturation and moisture because of the dew point temperature being reached. This results in more cloud cover and less sun. Not only are the days shorter with less sunlight, but more importantly, Ultra-Violet (UV) wavelengths from the sun disappear during this time due to the low angle of the sun, preventing UV from reaching the earth’s surface. [4]

Earth Orbit Around Sun

Hormone Regulation and Sleep

Research shows that bright sunlight plays an important role in our body’s ability to regulate serotonin levels. Serotonin is a hormone that determines our mood. It has been observed that people diagnosed with SAD have lower serotonin levels when compared to people without. [5] Low Vitamin D levels are also associated with SAD, mostly due to a lack of sunlight, specifically UV sunlight. [6] Interesting, isn’t it. Especially after learning that UV is unable to reach the earth’s surface during the winter months. Other findings suggest that people with SAD produce too much melatonin, which can lead to a lack of energy and increased sleepiness. [7] Although sleep is vital for optimal health, too much sleep can create imbalances, leading to a disruption in our overall well-being.

Ways to Combat SAD

Exposing your body to sunlight in the early morning hours, or anytime throughout the day, can help keep you mentally (and physically) healthy and strong. For locations that have less sunlight during the fall and winter months, light therapy can be a great solution in helping maintain healthy light levels. Exposure to bright white sources of light (at least 10,000 lux or greater) for 30 minutes has been shown to be effective in reducing the chance of developing SAD. Infrared light has also been shown to be effective. [8] Routine exercise, along with a healthy diet, are great factors as well in helping to keep your body healthy during the months when natural sunlight is more limited.

Does Joovv Help With SAD?

Joovv devices use wavelengths of red and near infrared light that are also present in natural sunlight. These clinically proven wavelengths of light help promote healthy cellular function, giving your body the ability to feel more energized. Joovv makes it easy and convenient to maintain healthy light levels, especially during the dark and gloomy months of the year. And the best part is, you can treat when it works best for you. To learn more about Joovv and the science behind how red light therapy works, click here

Joovv Mini 3.0


Seasonal Affective Disorder (SAD) can impact us all in various ways, usually putting a damper on our mood and reducing the amount of energy we have on a daily basis. Research shows SAD is directly impacted by season change, specifically lack of sunlight exposure, which we can link back to the angle of the sun. A great way to combat the mood changes associated with SAD is to maintain healthy light levels. This can be done by spending time outdoors in the sun, or by incorporating a red light therapy device like Joovv into your daily routine. Exposing the body to healthy light can be a great way to stay energized and positive during the months when sunlight is at its weakest. 



[1]  National Institutes of Mental Health. Seasonal Affective Disorder. NIH Publication No. 20-MH-8138. Accessed 17 February 2023.

[2] Pidwirny, M. (2006). "Earth-Sun Relationships and Insolation". Fundamentals of Physical Geography, 2nd Edition. Accessed 17 February 2023. 

[3] National Weather Service, National Oceanic and Atmospheric Administration. What Causes the Seasons? Accessed 17 February 2023.

[4] IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Radiation. Lyon (FR): International Agency for Research on Cancer; 2012. (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, No. 100D.) SOLAR AND ULTRAVIOLET RADIATION. Accessed 17 February 2023.

[5] Sansone RA, Sansone LA. Sunshine, serotonin, and skin: a partial explanation for seasonal patterns in psychopathology? Innov Clin Neurosci. 2013 Jul;10(7-8):20-4. PMID: 24062970; PMCID: PMC3779905. Accessed 17 February 2023.

[6] Penckofer S, Kouba J, Byrn M, Estwing Ferrans C. Vitamin D and depression: where is all the sunshine? Issues Ment Health Nurs. 2010 Jun;31(6):385-93. doi: 10.3109/01612840903437657. PMID: 20450340; PMCID: PMC2908269. Accessed 17 February 2023.

[7] Rosenthal NE, Sack DA, Jacobsen FM, James SP, Parry BL, Arendt J, Tamarkin L, Wehr TA. Melatonin in seasonal affective disorder and phototherapy. J Neural Transm Suppl. 1986;21:257-67. PMID: 3462335. Accessed 17 February 2023.

[8] Nussbaumer‐Streit B, Forneris CA, Morgan LC, Van Noord MG, Gaynes BN, Greenblatt A, Wipplinger J, Lux LJ, Winkler D, Gartlehner G. Light therapy for preventing seasonal affective disorder. Cochrane Database of Systematic Reviews 2019, Issue 3. Art. No.: CD011269. DOI: 10.1002/14651858.CD011269.pub3. Accessed 07 February 2023.

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