Take care not to get SAD
Recognizing Seasonal Affective Disorder, and possible ways of dealing with it this winter.
As the winter months rage on, and the hectic rush of the holidays draw ever closer, it’s easy to get frustrated, upset, and begin to feel rather depressed.
Such is the danger that is Seasonal Affective Disorder, or SAD (a rather apt acronym), which is categorized as a recurrent major depressive disorder usually manifesting during times of reduced natural light, starting from the later fall months and entering into winter.
SAD is rather common, with some numbers suggesting 5% of Americans experiencing SAD, but other numbers suggest up to 10-20% Americans experiencing SAD in some form, or millions of Americans.
Given everything going on it may be worth looking into SAD and seeing if this is something you may be experiencing yourself.
What is SAD?
Diagnosis of SAD, according to the Diagnostic and Statistical Manual on Mental Disorders (DSM-V) differentiates SAD from other depressive disorders based on whether the symptoms are gone for the rest of the year (full remittance) aside from the designated months. At least 2 years of seasonal depressive symptoms, with more seasonal depressive symptoms than symptom remittance throughout one’s life are used to evaluate and confirm a SAD diagnosis.
Some of the symptoms of SAD are similar to major depressive disorder only differing in seasonality of SAD symptoms (from Mayo Clinic).
Although SAD is usually referenced as a winter disease, there are spring/summer SAD symptoms as well which includes irritability and insomnia. However, the manifestation of spring/summer sad is likely to be different than for winter SAD. This review will look at winter SAD in particular, so keep that in mind moving forward.
Causes of SAD
As noted, the cause of SAD is likely due to reduced sun exposure. How this lack of sun exposure leads to SAD is rather varied.
For one, exposure to natural light keeps serotonin/melatonin levels in balance, as noted in my post on turkey and sleepiness, which may affect circadian rhythm and make one more fatigued and sleepy during the day.
Both molecules use L-tryptophan as a precursor, and serotonin is eventually modified into melatonin through the enzyme arylalkylamine-N-acetyltransferase (AA-NAT), as well as another enzymatic modification needed (shown below)1.
It’s suspected that AA-NAT is regulated by sunlight, such that sunlight helps to downregulate AA-NAT production and keep serotonin levels high. Then, in low sunlight AA-NAT is upregulated and melatonin synthesis occurs. Note that this process occurs predominately in the pinealocytes of the brain, and other biochemical processes are occurring that are likely to influence serotonin/melatonin levels such as adrenergic responses.
However, if this assumption is true then it explains why reduced sunlight can cause SAD, as AA-NAT expression will increase in reduced light and therefore increase melatonin production leading to sleepiness and fatigue.
Interestingly, it appears that serotonin reuptake transporters (SERT) may be increased in the winter months, which increase reuptake of serotonin from the synaptic cleft back into the presynaptic terminal of the preceding neuron. Essentially, this reduces serotonin signaling and may be responsible for some of the depressive symptoms experienced in the winter.
These points are summarized in a review from Melrose, S.2 below:
People with seasonal affective disorder have difficulty regulating the neurotransmitter serotonin, a neurotransmitter believed to be responsible for balancing mood [2]. In one study, people with SAD had 5% more SERT, a protein that assists with serotonin transport, in the winter months than in summer [2]. SERT transports serotonin from the synaptic cleft to the presynaptic neuron, so higher SERT levels lead to lower serotonin activity, thus causing depression [2]. Throughout the summer, sunlight generally keeps SERT levels naturally low [2]. But as sunlight diminishes in the fall, a corresponding decrease in serotonin activity also occurs.
People with SAD may also have difficulty with overproduction of melatonin [3]. Melatonin is a hormone produced by the pineal gland that responds to darkness by causing sleepiness [4]. As winter days become darker, melatonin production increases and, in response, those with SAD feel sleepy and lethargic [5]. Although melatonin likely plays a role in impacting the symptoms of SAD, it cannot by itself account for these phenomena [6].
The combination of decreased serotonin and increased melatonin impacts circadian rhythms. Circadian rhythms or the body's internal 24-hour “clock” are synchronized to respond to the rhythmic light–dark changes that occur daily and throughout each of the seasons. For people with SAD, the circadian signal that indicates a seasonal change in day length has been found to be timed differently, thus making it more difficult for their bodies to adjust [7–9].
Of course, reduced sunlight also means reduced Vitamin D production, and it’s likely that reduced serum Vitamin D levels may contribute to depressive symptoms.
Part of this may stem from Vitamin D’s activity as a hormone, which may mean hormonal disruption in reduced sunlight and low Vitamin D, leading to altered neuroendocrine function.
Also, Vitamin D appears to play a role in regulating serotonin synthesis, likely by increasing expression of the enzyme tryptophan hydroxylase (TPH2) which converts tryptophan into 5-hydroxytryptophan as noted in the above scheme3.
Omega-3 fatty acids may also appear to play a critical role in this process as well, a noted in the figure below from Patrick, R. P., & Ames, B. N. In particular, EPA appears to increase release of serotonin while DHA increases membrane fluidity, making postsynaptic serotonin receptors more accessible to serotonin. As such, both Vitamin D and omega-3 fatty acids may be critical for alleviating symptoms of SAD:
Research continues to find other reasons for SAD, and the hypotheses above are subject to change as new evidence comes to light, but so far it’s clear that light is a critical reason for the symptoms of SAD.
Dealing with SAD
With the knowledge above we can see a few factors that may attenuate SAD, including antidepressants, light therapy, and Vitamin D supplementation. It’s important to remember that treatment options should be discussed with appropriate professionals, and that the information here is intended to be informative and not medical advice.
With that, we can look at a few possible options generally used to help with SAD.
1. Antidepressants
Given that there’s a possibility of SERT elevation during winter months, and therefore reduced circulating serotonin one option would be to take antidepressants/SRIs, which may help increase serotonin levels within the synaptic cleft.
In theory, it would make sense to treat symptoms of depression with an antidepressant, and it’s likely to be an easy, quick option for may.
However, the use of pharmaceuticals may raise concerns over adverse reactions such as serotonin syndrome4, which are adverse reactions due to high levels of serotonin. There could also be a concerns about dependency and withdrawal symptoms, especially given that the use of this medication would be relegated to the season that one experiences SAD.
Again, it’s important to talk with a healthcare provider to see which option is best, but given some of these factors it may be worth considering other options before turning to pharmaceuticals.
2. Light Therapy
If lack of light may be a problem, more light may be the solution.
Light therapy, aka phototherapy or bright light therapy, utilizes light that imitates regular, full-spectrum sunlight (no UV-light) in order to produce the same effects and benefits as sunlight. Duration of light therapy varies, as well as the timing of the light.
Typical treatment requires placing a light source, such as a lamp or a box, nearby for a set period of time in order to receive adequate exposure.
Light therapy appears to be one of the main methods of tackling SAD, and it’s easy to purchase light boxes or lamps making it highly accessible.
Similar to regular sunlight, one just has to be careful of photosensitive medications or skincare when in the presence of a light box/lamp. However, aside from that many side effects from light therapy are minimal, usually similar to that of sunlight exposure.
3. Vitamin D Supplementation
Given that Vitamin D deficiency is a widespread problem, and that lack of sunlight is associated with reduced Vitamin D production, it seems like an obvious idea to consider supplementation with Vitamin D or consumption of foods rich in Vitamin D, such as oily fish and dairy products.
The actual dietary requirement for Vitamin D is highly varied among individuals, and some people consider a high course of Vitamin D supplementation followed by a maintenance level as being the best choice to increase serum levels. However, this may not be sustainable for many who may rather choose to take a fixed number of supplements per day without having to worry about adjusting for number of supplements.
There have been a few questions as to whether supplementation may actually be beneficial, but given that Vitamin D is a pivotal hormone in overall health, including immune function, it may be worth considering supplementing even if the benefits don’t translate over to alleviating symptoms of SAD.
It may be good to get Vitamin D levels checked and discussed with healthcare providers, but regardless this may also be one of the easiest options given how easily accessible and relatively cheap supplements can be.
Don’t get SAD
Other options to treat SAD are likely to be available, and a few different approaches may need to be taken in order to help with SAD. Note that the longer lack of light and Vitamin D supplementation goes on the worse many of the symptoms of SAD may become. It’s important to be aware if one is susceptible to SAD, or if one is experiencing SAD already.
In any case, given all of the frustration and moroseness that surrounds us it’s important to check one’s mental health. The holiday season can bring much joy, but it can also bring a lot of stress or additional anger and resentment.
Remember to take account of one’s own health, and to take measures that can help during the winter season so that you don’t become SAD.
Additional Resources
SAD Assessment Questionnaire
Diagnosis of SAD seems to rely on The Seasonal Pattern Assessment Questionnaire (SPAQ), as noted by Melrose, S. The questionnaire is freely available online, although it’s important to remember that assessment of the questionnaire is highly subjective and depends upon the therapist/doctor doing the assessment.
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Vasey, C., McBride, J., & Penta, K. (2021). Circadian Rhythm Dysregulation and Restoration: The Role of Melatonin. Nutrients, 13(10), 3480. https://doi.org/10.3390/nu13103480
Melrose S. (2015). Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depression research and treatment, 2015, 178564. https://doi.org/10.1155/2015/178564
Patrick, R. P., & Ames, B. N. (2015). Vitamin D and the omega-3 fatty acids control serotonin synthesis and action, part 2: relevance for ADHD, bipolar disorder, schizophrenia, and impulsive behavior. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 29(6), 2207–2222. https://doi.org/10.1096/fj.14-268342
Simon LV, Keenaghan M. Serotonin Syndrome. [Updated 2022 Jul 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482377/
As for the DSMIV book, it has grown like a malignant stage IV tumour. Not from knowledge so much as human arrogance and narcissism which has led us into the slope to hell.
All my journals over all those years became less readable. A waste of my attention. The same old crap, over and over. Authors getting points for a “peer-reviewed Update”. Enough.
Any relationship to SAD -- "Standard American Diet"? One sometimes should wonder what life would be like if we hadn't been poisoned so much.
There is more to the poisoning than diet, but that is a biggie. Pharmaceuticals are too. I had not given a thought in years to SAD (Seasonal Affective Disorder) until I read your post. Any tendency toward SAD seems to have passed after eliminating bad food, pharmaceuticals, and toxic household products, and reducing EMF/EMI.
On the other hand, reading the uncensored news can still be depressing, not to mention anxiety-inducing, in any season.