How Seasonal Affective Disorder Affects Sexual Desire

As daylight hours shorten and the weather turns colder, it’s possible that you may have noticed a shift in your overall mood, or that you feel more tired, unmotivated, and depressed than usual. For some, this shift may significant enough that it meets the criteria for Seasonal Affective Disorder (i.e., SAD), which is a pattern of recurring depressive episodes in a specific season (most often occurring in the Fall or Winter).

Classic symptoms of SAD include depressed mood, fatigue or low energy, poor sleep quality, carbohydrate cravings and/or weight gain, and diminished interest or pleasure in activities, including sex. In addition, another common SAD symptom includes low libido or reduced sexual desire [1]. Today on the blog, we’re going to examine SAD’s impact on sexual desire.

What Does The Research Say?

Animal Evidence

A 2019 study with rats used different durations of lighting to simulate winter versus summer light exposure [2]. Under low daytime light intensity (i.e., the winter condition), males displayed fewer mounts and intromissions (a proxy for sexual activity) compared with those under high light intensity (i.e., the summer condition). The authors suggest the reason for this decreased sexual behavior likely involves changes in brain regions tied to sexual motivation in the winter condition. Although this research wasn’t conducted in humans, it provides plausible biological support for the notion that seasonal shifts in lighting (which subsequently affects brain chemistry) may suppress sexual behavior.

Clinical Evidence

Overall, there is somewhat limited research on how Seasonal Affective Disorder impacts human sexual desire and behavior. However, we know from prior research that there is a strong link between depression and sexual functioning (more often than not, it tends to reduce libido and sexual behavior) [3], and some review articles of SAD do mention loss of libido as a potential symptom [4].

However, we do know from studies of light exposure that there is indeed an important link there with sexual desire. For example, in one study, researchers in Italy recruited 38 men diagnosed with hypoactive sexual desire disorder or sexual arousal disorder (both characterized by low sexual desire) and assigned them to either an experimental group (who received bright-light therapy) or a control group (who received significantly less light). The men received this bright or low light treatment each morning for 30 minutes over two weeks. The researchers found that the bright light therapy group showed both a rise in testosterone levels and higher self-reported sexual satisfaction compared to those who received less light [5].

Similarly, in another set of studies previously covered on the blog, researchers found that controlled sunlight exposure was also related to testosterone levels. Specifically, both men and women who spent about a half hour each day in the sun for two days showed a rise in testosterone compared to those who avoided sun exposure. Likewise, in a separate study of men and women receiving UVB phototherapy, participants reported an increase in passionate love following treatment.

So, while there is no large body of research that has specifically measured seasonal changes in libido in diagnosed SAD patients, there is a body of research pointing a likely link between light exposure, sex hormones, and sexual desire. Although women have higher self-reported rates of SAD (and therefore may experience more changes in libido as a result) [6], the results of the research so far suggest that treatment with light exposure has similar effects on men’s and women’s sexuality.

The decrease in desire that appears to result from reduced light exposure may stem from multiple factors. This can include lower levels of testosterone, lack of motivation, or other symptoms of depression (e.g., fatigue, poor sleep, social withdrawal). In addition, lower sunlight exposure may stimulate less production of serotonin in the brain, which could be another factor playing a role in feelings of mood and desire.

Conclusion

While more research is needed, the available evidence suggests a plausible connection between sunlight exposure, seasonal mood changes, and sexual desire. So if you notice your sex drive declines when the days shorten or your mood dips, you’re not alone. Consider paying attention to your sleep quality, the amount of sunlight you receive, and your general health habits. And if your symptoms are severe and distressing, consult with a healthcare provider, who can advise on whether phototherapy might be right for you. Recognizing and addressing the seasonal/mood component can be a helpful part of promoting sexual well-being throughout the year.

If you are experiencing symptoms of seasonal depression, please consult your healthcare provider.

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References:

1. Eagles, J. M. (2004). Seasonal affective disorder: a vestigial evolutionary advantage? Medical Hypotheses, 63(5), 767–772. https://doi.org/10.1016/j.mehy.2004.07.002
2. Lonstein, J. S., Linning-Duffy, K., & Yan, L. (2019). Low daytime light intensity disrupts male copulatory behavior, and upregulates medial preoptic area steroid hormone and dopamine receptor expression, in a diurnal rodent model of seasonal affective disorder. Frontiers in Behavioral Neuroscience, 13, 72. https://doi.org/10.3389/fnbeh.2019.00072
3. Jupe, T., Giannopoulos, I., & Roumpou, A. (2024). Sexual dysfunction, depression, and the impact of antidepressants. European Psychiatry, 67(S1), S539–S540. doi:10.1192/j.eurpsy.2024.1120
4. Attar-Levy D. (1998). Les dépressions saisonnières [Seasonal depression]. Therapie, 53(5), 489–498.
5. European College of Neuropsychopharmacology (ECNP). (2016, September 19). Lack of interest in sex successfully treated by exposure to bright light. Retrieved November 5, 2025 from www.sciencedaily.com/releases/2016/09/160918214443.htm
6. Chotai, J., Smedh, K., Johansson, C., Nilsson, L. G., & Adolfsson, R. (2004). An epidemiological study on gender differences in self-reported seasonal changes in mood and behaviour in a general population of northern Sweden. Nordic Journal of Psychiatry, 58(6), 429–437. https://doi.org/10.1080/08039480410006052