Depression
Springtime Can Instigate Seasonal Mood Problems
While counterintuitive, more daylight can be as damaging to mood as darkness
Posted April 3, 2024 Reviewed by Ray Parker
Key points
- Seasonal mood problems aren't limited to depression in the winter.
- People can experience depression or mania in response to decreasing or increasing sunlight.
- Seasonal mood changes are predictable, and therefore intervention, can be pre-planned, helping ward it off.
In the northern hemisphere, flowers are starting to blossom; days are warmer and getting longer. Spring is in the air. And, for some, an increase in mood disturbance (record screeches to a halt).
That’s right. "seasonal affective disorder," or SAD, frequently assumed to mean depressive episodes that occur with waning sunlight, can rear its head as sunlight increases (e.g., Galima et al., 2020; APA, 2022). While a much rarer phenomenon than the winter version, the suffering is just the same.
Before going further, it must be noted that SAD is not an actual diagnosis. It's popular shorthand for the "with seasonal pattern" specifier for major depressive disorder and bipolar disorder. For the sake of simplicity, though, SAD will be used from here on in.
The SAD Facts
While popularly used to describe a winter mood slump, it should be understood that SAD is not synonymous with “winter blues.” Many people feel a little less motivated, perhaps seek comfort food, and sleep a bit more in the winter. If they’re not a winter sports enthusiast, they might be grumpy, awaiting what they consider nice weather. The increased sleeping and eating in some could even be a remedy for boredom. It becomes disordered when one’s mood significantly impacts one's ability to function optimally. In short, depression-type SAD involves major mood episodes (MDE).
Clinically, SAD, while an appropriate anacronym to suit the affliction of wintertime MDE, is not limited to depression. “Affective disorders” is synonymous with mood disorders, and there are two categories, depressive and bipolar; the latter, of course, means MDE cycling with mania (also known as manic-depression).
Given it is seasonal affective disorder and not winter affective disorder, SAD, collectively, means that people can have MDE or hypomanic/manic experiences as light fades and/or as light increases. In short, SAD means that there is a pathological mood alteration correlated to a seasonal shift. Some people’s moods might only shift with the seasons, while others who are prone to depression or bipolar disorder throughout the year could also bank on a mood shift with a season.
But Why?
As for why seasons have an effect on moods, it seems largely influenced by biological factors. This is not to say it cannot be rooted in psychogenic factors. For example, someone might have an annual “anniversary” effect from a depressing event that occurred in a certain season but feels great the rest of the year.
In terms of biological influences, seasonal depression is particularly associated with vitamin D (e.g., Alghamdi, 2019; Petric, 2021), which our skin naturally produces with sunlight. Vitamin D is associated with the regulation of a serotonin transporter called SERT (also called 5-HTT).
As most people are aware, serotonin is correlated to healthy moods; antidepressants generally help increase the presence of this neurotransmitter. Neurotransmitter transporters are like escorts, or perhaps more like bouncers, in this case, ushering the serotonin out of the brain receptors. Interested readers can learn more about seasonal SERT in research by McMahon et al. (2016).
In the winter, the lack of sunlight means less vitamin D, so there’s less regulation of SERT. It can be like too many ushers looking for something to do, so they all go moving serotonin out prematurely. This leaves empty receptors, impacting mood. In terms of depression, this is analogous to some of the fuses in a fuse box being left out; there will be some electricity for the lights and equipment in the building, but it won't be optimal.
Mania, too, has been associated with serotonin (e.g., Shiah & Yatham, 2000; Cleveland Clinic, 2022). Serotonin is an emotional stabilizer and thus could help regulate “activating” neurotransmitters/hormones, which can easily run amok in people prone to mania, contributing to agitated/euphoric states.
In the summer, longer daylight means more vitamin D is present, which might lead to over-regulation of SERT in those prone to it. While no hard evidence has been discovered, it makes sense that, in this case, there may not be as much transportation of serotonin, causing a barrier to healthy moods.
One theory that has been researched about spring/summer mania (e.g., Wang &Chen, 2013) is an oversensitivity to bright light that suppresses melatonin production. Melatonin, a derivative of serotonin, is an important sleep hormone. With the waning sunlight each day, our bodies begin to secrete melatonin to wind us down, like slowly pulling down a shade. Early morning sunlight is like pulling up a shade, flooding us with energy for the day. Sticking with the metaphor, if the shade never gets pulled down, there’s no going to bed, and lack of sleep is highly correlated to instigating mania in bipolar disorder.
Clinical Implications
With the above in mind, it is important to pay attention to seasonal patterns of mood changes. If they are established patterns, they’re predictable and can be prepared for, hopefully leading to less suffering, perhaps even cutting it off at the pass.
If someone with bipolar disorder is prone to seasonal MDE, it is particularly important to prevent an episode. This is because, in bipolar disorder, MDE often upcycles into manic or mixed episodes, setting off a chain of cycling moods.
The following tips can serve as a SAD first aide kit, helping therapists and sufferers alike plan for managing seasonal moods:
- People prone to seasonal mood shifts may already be on antidepressants or mood stabilizers (the latter in the case of bipolar disorders) throughout the year but may wish to meet with the doctor more often during the particular season. Those whose mood strictly changes with the season might find a pharmaceutical helpful just for that period. Some people I've worked with met with a psychiatrist about a month in advance of when they usually began feeling the mood change to begin the medication, and two or three months later to taper off for the rest of the year.
- Return to therapy or pre-schedule more appointments during the period.
- Nutritional changes can also help, such as having one's primary care doctor order a vitamin/mineral panel test. If folate and vitamins E and D are low, which is associated with depression, meeting with a nutritionist could increase optimal levels.
- Talking to a psychiatrist about using a vitamin D lamp.
- If prone to seasonal mania, it could be helpful to be very rigid about sleep hygiene.
- Lifestyle changes can also be planned:
For example, if, when depressed, exercise wanes, make sure you have a workout partner to keep you accountable in the gym; as we know, exercise mitigates depression.
Similarly, if social contact or involvement in hobbies lags, having friends and family to keep you moving can assist with structure and meaningful activity in lieu of isolating and ruminating.
Disclaimer: The material provided in this post is for informational purposes only and is not intended to diagnose, treat, or prevent any illness in readers or people they know. The information should not replace personalized care or intervention from an individual's provider or formal supervision if you're a practitioner or student.
References
Alghamdi, S., Alsulami, N., Khoja, S., Alsufianai, H., Tayeb, H.O., & Tarazi, S.I. (2020). Vitamin d supplementation ameliorates severity of major depressive disorder [abstract]. Journal of Molecular Neuroscience, 70, 230–235. https://doi.org/10.1007/s12031-019-01461-2
American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.).
Galima, S.V., Vogel, S.R., &Kowalski, A.W. (2020). Seasonal affective disorder: Common questions and answers. American Family Physician, 102(11), 668-672. https://www.aafp.org/pubs/afp/issues/2020/1201/p668.html
McMahon, B., Andersen, S.B., Madsen, M.K., Hjordt, L.V., Hageman, I., Dam, H., Svarer, C., da Cunha-Bang, S., Baaré, W., Madsen, J., Hasholt, L., Holst, K., Frokjaer, V.G., & Knudsen, G.M. (2016). Seasonal difference in brain serotonin transporter binding predicts symptom severity in patients with seasonal affective disorder. Brain, 139(5), 1605–1614, https://doi.org/10.1093/brain/aww043
Petric, D. (2021). The importance of vitamin d in seasonal affective disorder and other depressive disorders. International Journal of Medical Reviews and Case Reports, 5,(1). DOI: 10.5455/IJMRCR.TheImportanceofVitaminDinSeasonalAffectiveDisorderandotherdepressivedisorders.
Shiah, I-S., & Yatham, L., (2000). Serotonin in mania and in the mechanism of action of mood stabilizers: A review of clinical studies. Bipolar Disorders, 2, 77-92. 10.1034/j.1399-5618.2000.020201.x.
Wang, B. & Chen, D. (2013). Evidence for seasonal mania: A review. Journal of Psychiatric Practice 19(4), 301-308. DOI: 10.1097/01.pra.0000432600.32384.c5