8 Facts About Seasonal Affective Disorder

iStock/Martin Dimitrov
iStock/Martin Dimitrov

As the winter days get colder, some look forward to making snow angels and curling up with a mug of hot chocolate. But for millions of people, winter brings debilitating depression and lethargy. Seasonal Affective Disorder (SAD) is thought to affect 6 percent of the U.S. population, with millions more having milder forms of seasonal malaise. Here’s what you need to know about this condition.

1. Seasonal affective disorder is a relatively recent diagnosis.

Doctors have commented on the seasonality of depression in their patients for hundreds of years. The 19th-century psychiatrist Jean-Étienne Esquirol described a Belgian man whose life was generally good, but “at the beginning of autumn [he] became sad, gloomy, and susceptible,” and this pattern had continued for years. Esquirol prescribed a trip to the south of France and then into Italy as winter progressed. In May, the patient returned to Paris “in the enjoyment of excellent health.”

The modern understanding of SAD, however, didn’t emerge until the 1980s. A 1981 article in the Washington Post described a patient who was “almost dysfunctional in the winter, with both her mood and her energy levels at low levels.” It added that Norman Rosenthal, a researcher at the National Institute of Mental Health, “would like to hear from anyone with distinctly seasonal mood disorders. Applicants will be sent questionnaires, from which participants will be selected” for an experimental treatment program.

Decades later, Rosenthal told the Washington Post, “I thought I was dealing with a very rare syndrome. […] We got 3000 responses from all over the country.” In 1984 Rosenthal and colleagues identified SAD in the journal Archives of General Psychiatry, and in 1987 it was added to the American Psychiatric Association’s manual DSM-III-R.

2. Seasonal affective disorder doesn’t just happen in winter.

In the APA's current DSM (DSM-5), one benchmark for diagnosing depressive disorders “with seasonal pattern” is “a regular temporal relationship between the onset of major depressive episodes in major depressive disorder and a particular time of the year (e.g., in the fall or winter).” It also indicates that there must be no seasonally related stressors (such as consistent unemployment in winter), that full remission occurs at “a characteristic time of the year,” and that the pattern has repeated for two years without non-seasonal episodes.

Nothing in that definition requires winter, however. An estimated 10 percent of people with SAD experience the opposite of the conventional diagnosis—their depression appears in spring and summer. And in places like the Philippines, studies have found more people feel their worst in summer rather than in winter [PDF].

According to the National Institute of Mental Health, summer-onset and winter-onset SAD can even have different symptoms. Winter symptoms can include oversleeping, weight gain, carbohydrate cravings, and low energy, while summer symptoms might be poor appetite, insomnia, agitation, anxiety, and even violent behavior.

3. It’s also not the ‘winter blues.’

SAD is not the same as feeling a little down as it gets gloomy outside. A SAD diagnosis meets all the criteria for major depression and should be treated as seriously—the only difference is that SAD has a seasonal pattern. Psychiatrists do recognize ‘winter blues,’ or sub-syndromal SAD (S-SAD), for “individuals who do not meet diagnostic criteria for depression during the fall/winter months, but who experience mild to moderate symptoms during fall or winter,” SAD expert Kelly Rohan told the APA. This form may affect an additional 15 percent of the US population. (This number is highly dependent on where the S-SAD patients live, however.)

4. Your chance of experiencing SAD depends on your latitude (to a point).

It might seem obvious that as you get further north—to regions with colder, darker, and longer winters—SAD would be more prevalent. There is some evidence for this: An estimated 1 percent of Floridians experience SAD compared to 9 percent of Alaskans. But one study in Tromsø, in northern Norway, found “no significant differences in the reporting of current mental distress depending on season” (although they did find people had more sleeping problems in winter). Icelanders also have remarkably low instances of SAD. Even more surprisingly, people of Icelandic descent living in Canada have a lower prevalence of SAD than non-Icelandic Canadians in the same area [PDF].

5. Not everyone in a region is affected the same way.

SAD is reported to affect four times as many women as men, and a recent pilot study indicated vegetarianism may also be associated with SAD. The researchers found that:

“The percentage of SAD patients among Finnish vegetarians was four times higher than in the normal population. The percentage of vegetarians among the SAD patients in a Dutch outpatient clinic was three times higher than in the normal population. In the Dutch population, the seasonal loss of energy, in particular, is related to vegetarianism.”

Some factors may confound the data (for example, it’s possible vegetarians are more likely to forgo antidepressants, so there are more of them in outpatient facilities), but the researchers say the findings suggest a link. In fact, one theory for Iceland’s low SAD rate suggests that Icelanders’ fish-heavy diet may have a protective effect (and Icelanders living in Canada might be sticking with their traditional foods).

6. We don’t know what causes seasonal affective disorder.

While scientists haven’t figured out what factors cause SAD, the most popular theory is the phase shift hypothesis: That, due to later sunrises and earlier sunsets, the body’s circadian rhythms sometimes get out of whack with its sleep/wake cycles, like a several-months-long jet lag. It’s also possible that people with winter SAD can’t regulate serotonin or they overproduce melatonin, and the imbalance alters circadian rhythms.

7. Luckily, seasonal affective disorder is treatable.

For years, the gold standard of SAD treatment has been light therapy. The process involves sitting near a light box for around 30 minutes after you wake up. Your eyes are open, but not looking directly at the light, meaning the therapy can be done while watching TV, reading a newspaper, or having breakfast.

But researchers warn again self-treating with light therapy—it can negatively affect people with bipolar disorder or eye problems. And, light boxes must be made specifically for treating SAD. Many commercially available light boxes release predominantly UV light, and SAD boxes should release as little UV as possible.

More recently, research has been looking into Cognitive Behavioral Therapy (CBT)—a technique that alters negative thoughts to manipulate emotions and behaviors, like changing your thinking from “I hate winter” to “I prefer summer.” With CBT, some researchers have seen fewer recurrences, less-severe symptoms, and higher remissions compared to light therapy users. Antidepressants are also prescribed for SAD.

8. SAD may have once been an evolutionary advantage.

In the 1981 Washington Post article, the SAD sufferer commented that she “should have been a bear” because “bears are allowed to hibernate, and people aren’t.” As the years went on, some proposed that the symptoms of winter SAD—sleeping more, being less active, and eating fattening foods—could be a vestigial hibernation instinct. Many dismissed that explanation, but in the early 2000s things began to change. A Russian study found that women without depression and with non-seasonal depression consumed around the same amount of oxygen, while women with winter depression consumed less [PDF]. Doctors began to think SAD exists today because it once offered some evolutionary benefit for humans surviving winter.

One proposed benefit is reproduction. People with winter SAD are lethargic in winter but generally active in spring and summer, which increases the probability of procreation in those seasons. If a child is conceived between May and September, that means a high probability of being born between February and June, which some researchers propose would increase chances of survival before winter kicks in. Meanwhile, Robert Levitan at the University of Toronto “consider[s] SAD to be an evolutionary disorder, an energy-conserving process that is no longer helpful in modern society. While in modern times it’s not good for us to slow down too much in the winter, or to gain lots of weight, this probably helped our ancestors survive in the ice age.”

10 of the Best Indoor and Outdoor Heaters on Amazon

Mr. Heater/Amazon
Mr. Heater/Amazon

With the colder months just around the corner, you might want to start thinking about investing in an indoor or outdoor heater. Indoor heaters not only provide a boost of heat for drafty spaces, but they can also be a money-saver, allowing you to actively control the heat based on the rooms you’re using. Outdoor heaters, meanwhile, can help you take advantage of cold-weather activities like camping or tailgating without having to call it quits because your extremities have gone numb. Check out this list of some of Amazon’s highest-rated indoor and outdoor heaters so you can spend less time shivering this winter and more time enjoying what the season has to offer.

Indoor Heaters

1. Lasko Ceramic Portable Heater; $20

Lasko/Amazon

This 1500-watt heater from Lasko may only be nine inches tall, but it can heat up to 300 square feet of space. With 11 temperature settings and three quiet settings—for high heat, low heat, and fan only—it’s a dynamic powerhouse that’ll keep you toasty all season long.

Buy it: Amazon

2. Alrocket Oscillating Space Heater; $25

Alrocket/Amazon

Alrocket’s oscillating space heater is an excellent addition to any desk or nightstand. Using energy-saving ceramic technology, this heater is made of fire-resistant material, and its special “tip-over” safety feature forces it to turn off if it falls over (making it a reliable choice for homes with kids or pets). It’s extremely quiet, too—at only 45 dB, it’s just a touch louder than a whisper. According to one reviewer, this an ideal option for a “very quiet but powerful” heater.

Buy it: Amazon

3. De’Longhi Oil-Filled Radiator Space Heather; $79

De’Longhi/Amazon

If you prefer a space heater with a more old-fashioned vibe, this radiator heater from De’Longhi gives you 2020 technology with a vintage feel. De’Longhi’s heater automatically turns itself on when the temperatures drops below 44°F, and it will also automatically turn itself off if it starts to overheat. Another smart safety feature? The oil system is permanently sealed, so you won’t have to worry about accidental spills.

Buy it: Amazon

4. Aikoper Ceramic Tower Heater; $70

Aikoper/Amazon

Whether your room needs a little extra warmth or its own heat source, Aikoper’s incredibly precise space heater has got you covered. With a range of 40-95°F, it adjusts by one-degree intervals, giving you the specific level of heat you want. It also has an option for running on an eight-hour timer, ensuring that it will only run when you need it.

Buy it: Amazon

5. Isiler Space Heater; $37

Isiler/Amazon

For a space heater that adds a fun pop of color to any room, check out this yellow unit from Isiler. Made from fire-resistant ceramic, Isiler’s heater can start warming up a space within seconds. It’s positioned on a triangular stand that creates an optimal angle for hot air to start circulating, rendering it so effective that, as one reviewer put it, “This heater needs to say ‘mighty’ in its description.”

Buy it: Amazon

Outdoor Heaters

6. Mr. Heater Portable Buddy; $104

Mr. Heater/Amazon

Make outdoor activities like camping and grilling last longer with Mr. Heater’s indoor/outdoor portable heater. This heater can connect to a propane tank or to a disposable cylinder, allowing you to keep it in one place or take it on the go. With such a versatile range of uses, this heater will—true to its name—become your best buddy when the temperature starts to drop.

Buy it: Amazon

7. Hiland Pyramid Patio Propane Heater; Various

Hiland/Amazon

The cold’s got nothing on this powerful outdoor heater. Hiland’s patio heater has a whopping 40,000 BTU output, which runs for eight to 10 hours on high heat. Simply open the heater’s bottom door to insert a propane tank, power it on, and sit back to let it warm up your backyard. The bright, contained flame from the propane doubles as an outdoor light.

Buy it: Amazon

8. Solo Stove Bonfire Pit; $345

Solo Stove/Amazon

This one is a slight cheat since it’s a bonfire pit and not a traditional outdoor heater, but the Solo Stove has a 4.7-star rating on Amazon for a reason. Everything about this portable fire pit is meticulously crafted to maximize airflow while it's lit, from its double-wall construction to its bottom air vents. These features all work together to help the logs burn more completely while emitting far less smoke than other pits. It’s the best choice for anyone who wants both warmth and ambiance on their patio.

Buy it: Amazon

9. Dr. Infrared Garage Shop Heater; $119

Dr. Infrared/Amazon

You’ll be able to use your garage or basement workshop all season long with this durable heater from Dr. Infrared. It’s unique in that it includes a built-in fan to keep warm air flowing—something that’s especially handy if you need to work without wearing gloves. The fan is overlaid with heat and finger-protectant grills, keeping you safe while it’s powered on.

Buy it: Amazon

10. Mr. Heater 540 Degree Tank Top; $86

Mr. Heater/Amazon

Mr. Heater’s clever propane tank top automatically connects to its fuel source, saving you from having to bring any extra attachments with you on the road. With three heat settings that can get up to 45,000 BTU, the top can rotate 360 degrees to give you the perfect angle of heat you need to stay cozy. According to a reviewer, for a no-fuss outdoor heater, “This baby is super easy to light, comes fully assembled … and man, does it put out the heat.”

Buy it: Amazon

Sign Up Today: Get exclusive deals, product news, reviews, and more with the Mental Floss Smart Shopping newsletter!

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Want to Fall Asleep Faster? Try This Breathing Technique

Andrea Piacquadio, Pexels
Andrea Piacquadio, Pexels

Struggling to fall asleep can feel like a hopeless battle. It often seems like the harder you try turning your brain off, the less likely it is to happen. One way to trick yourself into falling asleep fast is finding something to concentrate on other than how long you've been awake. For nights when your thoughts just won't stay quiet, try the 4-7-8 technique.

According to Simplemost, the 4-7-8 breathing method is meant to combat anxiety, restlessness, and other enemies of a good night's sleep. The actual technique is simple: Just inhale for four seconds, hold your breath for seven seconds, and exhale for eight seconds. Like counting sheep, measuring out your breaths gives your brain something to do that isn't obsessing about your hectic day or the day ahead.

Taking slow, deliberate breaths has also been proven to reduce stress. Neurons that influence calmness have been found in the breathing control centers of mouse brains. In humans, deep breathing has long been central to mindfulness practices like yoga and meditation. The 4-7-8 breathing technique functions as both a distraction from your thoughts and a way to combat any anxious sensations that may be keeping you awake.

The next time you find yourself tossing and turning at night, try anywhere between three and eight rounds of this breathing technique to calm your body and mind. And to get the best rest possible, make sure you're settling into the best sleep position for your health.

[h/t Simplemost]