“February is my favorite month.” said no one living in Boston ever. The short days, cold temperatures, and repetitive snow really throw a dagger (presumably made of ice) into good times. I tend to think of Dec-Feb as my hibernating months; I am more lethargic, less motivated, and my fiancé and labmates can vouch for the fact that I am slightly more irritable than the good natured loving person I always am in better weather. I’ve come to attribute my noticeable seasonal downswing to Seasonal Affective Disorder, or SAD (an acronym that ironically makes me quite happy), a self-diagnosis I probably made from seeing a commercial. Being the curious graduate student that I am I decided to do a little research on the subject and see what I could learn—really trying to go above and beyond what pharmaceutical advertising taught me.
SAD is most fundamentally defined as a major depressive disorder with a seasonal pattern. The criteria for SAD as described in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) include having this seasonal pattern of depression, with full remittance of symptoms during other seasons, for at least two years. Over a lifetime, someone struggling with winter SAD will have more depressed winter seasons than not. Risk factors include being female, being 18-30 years old, and living far from the equator. If you are curious as to how SAD is clinically diagnosed, you can take the Seasonal Pattern Assessment Questionnaire (SPAQ). Basically, the questionnaire asks you to report if a list of factors, such as sleep duration, social activity, mood, and energy level, changes with the seasons. After researching the disorder and taking the completely subjective questionnaire I decided I don’t have SAD, but perhaps I have a sub-condition, called subsyndromal SAD or S-SAD. A scientific review article referred to S-SAD as the “winter blues1.” Which made me wonder, who doesn’t have the winter blues? I passed along the questionnaire to the people I sit near in lab and indeed diagnosed 2 out of 3 of them with the winter blues (please note I am completely unqualified to do so) . Interestingly, this pattern fell along gender lines with the females (risk factor number 1) indicating changes in well-being and the male not so much. I’m sure my amateur study and N of 3 really enhances already existing data.
I know that feeling cold can make one unhappy, but beyond this how does the winter season actually affect our mood, our appetites, our sleep patterns, or our energy levels? Research points to shorter days as the root of the problem. Lack of sunlight has been associated with four big biological changes: decreased synaptic serotonin, increased melatonin, decreased Vitamin D, and altered circadian rhythms. Serotonin is a well-known modulator of mood and many common antidepressants such as Prozac work by increasing levels of this neurotransmitter in the brain. Melatonin is a key hormone in regulating our sleep cycles. Decreased Vitamin D insufficiency has been linked to clinically significant depressive symptoms. Almost all aspects of our physiology (sleep hormones, stress hormones, core body temperature, heart rate, etc.) are tied to or modulated by our 24 hour circadian rhythm. So the story seems to make sense–during winter we receive less sunlight, causing depressive moods, wreaking havoc to our body rhythms, and disrupting of our sleep cycles. Consequently, we have the winter blues.
I was totally buying it until I read this very recent article in New York Magazine in which the author proposes that the SAD story is merely an example of how our expectations can shape our experiences of the world. In other words, we may dislike winter, then hear about SAD, then self-diagnose and use it as an excuse to stay in bed for an extra hour. The author makes a very interesting case for dismissing SAD. The article cites a study published recently which surveys almost 35,000 adults in the U.S about their depression symptoms, and summarizes:
“the results provided no evidence whatsoever that people’s depression symptoms tended to be higher in winter — or at any other time of the year. This lack of a seasonal effect was true whether looking at the entire sample or only respondents with depressive symptoms. The respondents’ geographical latitude and sunlight exposure on the day of the survey were also unrelated to depression scores.”
I checked out the study and found that the survey given was the PHQ-8 (not the SPAQ), a questionnaire developed to assess depressive disorders. It seems to me that the researchers call into question not the alteration of mood during winter per se, but the categorization of SAD as a major depressive disorder and the validity of the SPAQ as a tool for assessing depression. The field may need to develop better tools in order to diagnose SAD and separate this DSM-5 major depressive disorder from the more general, and more expected, winter blues.
Aside from how the disorder is qualified in the DSM-5, I think there is a winter blues effect that many people can relate to. I believe more research is needed to link the subjective claims of SAD or S-SAD symptoms with the biological evidence of decreased serotonin, increased melatonin, and circadian rhythms to help us understand how sunlight, or lack thereof, may cause seasonal effects on psychopathology. It’s hard to ask these questions of causation in humans, but a study published in 2016 by a group in Peking University did address the issue in adolescent rats. When the rats were housed in conditions of a shorter photoperiod (akin to shorter days of winter) they exhibited anhedonia, elevation of the stress hormone cortisol, and elevation of melatonin. Their results certainly point to the idea that shorter winter days cause a real biological case of winter blues.
I’m interested to see how the debate plays out; is SAD a consequence of our own expectation or do the signaling molecules in our systems need sunlight to bolster a productive happy self? It may very well end up being a bit of both. In the meantime, I’ll work on these tips to ‘stay happy all season.’ And if that doesn’t work, I will keep reminding myself that Punxsutawney Phil forecasted an early spring!
- Melrose, S. (2015) Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depression Research and Treatment. 2015: 1-6.
- Oldham M. and Ciraulo D. (2014) Bright light therapy for depression: A review of its effects on chronobiology and the autonomic nervous system. Chronobiology International. 31(3): 305-319.
- Traffanstedt, M. et al (2016) Major Depression with Seasonal Variation: Is it a Valid Construct? Clinical Psychological Science. 1-10.
- Xu, LZ. et al (2016) Short photoperiod condition increases susceptibility to stress in adolescent male rates. Behavioural Brain Research. 300: 38-44.