An engineer with bipolar disorder tracked his moods for more than a decade and noted connections to seasonal patterns, which helped researchers identify SAD.

The study helped formalize research and diagnosis of seasonal affective disorder, catalyzing the development of therapies (like bright light) and leading to broader adoption of effective treatments. It also helped connect the influence of light and seasons on biological mechanisms in the human body, spurring exploration of circadian rhythms.

Norman Rosenthal led the team at the National Institute of Mental Health that first identified and described seasonal affective disorder in 1984. This 101 from NIMH explores the basics of the condition, from who develops it to how it is treated.

The South African doctor migrated to New York City in the 1970s. During his first winter there, he noticed the shorter days had a significant impact on his mood compared to those in his hometown of Johannesburg, South Africa, which is much closer to the equator. After three years of this seasonal mood shift, he decided to focus his studies. Hear him speak in this quick narration.

Despite its significantly lower incidence, summer-risk SAD is as significant as its winter counterpart. Rather than being prompted by less light, the summer version is typically spurred by high temperatures, strong light, distinct summer time social pressures (appearing in a bathing suit, for example), and pollen. Common treatments include keeping cool and prioritizing sleep.

Most people’s eyes become more sensitive to light in the winter months, but some do not. This failure to adjust causes ripple effects on those individuals’ biological clocks. This Ted-ED video provides a clear, brief, narrative explanation of the condition in six minutes.

Subsyndromal affective disorder is diagnosed when someone exhibits two of the nine major criteria for depression (but not more than five) as a result of seasonal changes. While it is milder than primary SAD, SSAD is still significant and impacts millions.

Using latitude, depression prevalence, and populations of women and those aged 18-30, this map shows the risk of experiencing seasonal affective disorder during the winter. Researchers weighted latitude most (50%) and demographics least (5% each for women and young adults). Overall risk is not a useful predictor of prognosis for an individual.

Those with ADHD—chronic issues with attention and executive function—are primed for SAD. Many are disproportionately evening chronotypes (more awake in the evening), have a delayed sleep phase, and have low sensitivity to light in the morning. This podcast explores the overlap between these two groups.

Researchers have confirmed what people have sensed for ages: Our emotions during the springtime can go a little wild. This piece breaks down the impact of the seasonal transition on our bodies and prescribes a few ways to mitigate the effects.

This prevalence trend mirrors the broader incidence of depression among women and is well-documented. Researchers suggest the disparity stems from differences in hormones, social role expectations, coping mechanisms, and more. Men may also present with depression differently, and seek help less.

Nothing is better than going outside and soaking up real sunlight. However, this is harder in winter, especially in very cold and cloudy regions. SAD lamps are designed to project 10,000 lux—a unit of illuminance, or how much light actually hits a surface (rather than how much is produced, like watts). This video discusses product options and practical considerations.

Schildkraut was one of the first to put forward this idea, which stemmed from lab animal research. A decade later, researchers published the first landmark paper on fluoxetine—better known by trade name Prozac—which increases serotonin levels in the brain.

Clinical trials showed a 44% reduction in risk for recurrence of SAD for those who took the drug compared to a placebo group. Bupropion is a norepinephrine–dopamine reuptake inhibitor, which increases dopamine (other common antidepressants, known as selective serotonin reuptake inhibitors, sometimes can suppress dopamine, but not always).

There are two types of this disorder. Bipolar 1 features a significant manic episode—abnormally elevated mood and frantic energy—followed by repeated depression, while Bipolar 2 vacillates between depressive episodes and hypomania, a milder form of mania, but not a full mania. Listen to this podcast as experts explain the condition.

Daylight saving time can interfere with a person’s sleep schedule, but it also has been linked to increased rates of depression, heart attack, stroke, cancer, and car accidents. UT Southwestern’s Dr. Joseph Takahashi explains why the time change is bad for your brain and health.

Meteorologists and climatologists define seasons differently from “regular” or astronomical spring, summer, fall, and winter. Traditional seasons reflect the movement of celestial objects, known as the astronomical seasons; meteorologists mark seasonal change based on temperature averages.

Giant pandas in locations outside their evolved latitudinal range (from southeast Asia to northern regions around Beijing) exhibit more sluggish behavior, even when they were born there. Researchers have observed that similar sensitivities to "photoperiods" (or time with light) impacts many animals, including birds, insects, and our pets.

An analysis of five adults participating in a German reality program that tasked them with living in a Stone-Age-like settlement for 2.5 months, provided some insights into how modern conditions may have shifted our circadian rhythms. The participants slept about 90 minutes more under these conditions, and went to bed earlier and rose earlier, raising questions about how circadian rhythms, sleep, and sleep quality are affected by modern lifestyles.

Circadian rhythms were first observed in the 1700s, when French astronomer Jean-Jacques D'Ortous de Mairan put a plant in a dark room and watched it still respond to day and night cycles, setting off further studies about specific light-dark biological cycles, an area of inquiry that continues today with the human "clock proteins" at the molecular level.

A study led by a team from Stanford University showed that MR can help people with depression by providing pathways to engage in activities such as digital board games and dancing. Participants saw reduced symptoms of depression that made their overall treatment plans more successful.

In this video, a Salk Institute Researcher offers daily habit tips focused on aligning with your circadian rhythms. She notes heart rate and blood pressure are highest in the afternoon, for example, and there’s a triglyceride peak in the morning. Generally, she says, it’s a good idea to schedule your doctor’s checkups at the same time of day each year so there’s consistency across your data.

Postmortem brain tissue analysis suggests there are genetic and epigenetic similarities between individuals with autism, schizophrenia and bipolar disorder. All three conditions appeared to have activation of genes in astrocytes and suppression of specific genes that function at the junction between neurons, called synapses.

A growing number of people on social media claim to have a perceptual condition that lets them smell colors, see music, or taste sounds. But do they really?

Although light and dark have the largest influence on circadian rhythms, temperature, stress, and certain medications are among the factors that also play a role. Persistent trouble sleeping or staying asleep may signal it’s time to see your doctor to get a better sleep-wake schedule.

Science suggests that early-morning exercise, later-morning peak work or social time, consistent exercise, and a "digital sunset"—starting to turn down the lights in the evening and avoid screens—are important for circadian health.

Astronauts aboard the International Space Station experience 16 daily sunrises, but scientists have learned to try to promote circadian rhythms by phasing through several light settings aboard the ISS to improve astronauts’ sleep and productivity.

Before professional standards were adopted, practitioners used varying criteria to diagnose mental health disorders. By the 1970s, more objective lists were organized, culminating in this list of polythetic criteria—a list of symptoms where no single criterion is required, but a minimum number must be present.

An icy water exposure can lead to the release of norepinephrine, cortisol, dopamine, and other stress hormones that are beneficial, among other potential effects. Some data shows that this type of exposure can help combat depression symptoms among some patients, but more research is still needed.

A 2025 study found that Antarctic krill, a food chain staple in the Southern Ocean, have an internal biological clock that helps regulate its swimming patterns and helps the tiny shrimp-like animals adapt to daily and seasonal environmental changes. Better understanding of how the clock and light cues interact may help scientists understand how well the species will respond to pronounced climate change in the polar region.

Dive into the basics on springtime including the astronomy that brings it about, natural signs of spring's arrival, and some of the cultural approaches to the season.

People differ in how they respond to setbacks. Famed psychologist Martin Seligman outlines three key pillars for resilience: developing mental toughness by interpreting failures as external and temporary, recognizing and using one’s signature strengths, and cultivating strong relationships that offer support and meaning.

Menopause, a natural biological process, occurs in three stages: perimenopause (hormone fluctuations), menopause (end of menstrual cycles), and postmenopause (12 months without menstruation). Hormonal shifts during this time can affect neurotransmitters, increasing the risk of mood disorders.

Scary rides stimulate our fight-or-flight response while simultaneously releasing feel-good endorphins like dopamine, serotonin, and oxytocin. Once we realize we're in a safe space, we can enjoy the ride and even feel confident and relieved by the accomplishment of overcoming a fearful feat.

Experiencing 15 sunrises and sunsets a day while aboard the International Space Station, visitors preserve their circadian rhythms and mental health with fixed timetables. Astronauts have described sleep as living in a vacuum cleaner due to ongoing air filtration.

A large analysis of existing studies published in 2021 found that systemic inflammation is associated with fatigue, appetite changes, and sleep disruption, rather than some of depression's broader symptoms including hopelessness about the future, or feeling fearful. This may suggest that inflammation influences specific symptoms of the condition, rather than the disease as a whole.

The perennial debate on how to be happy involves various aspects of life, and one of the most essential is our psychological attitudes toward experiences. This piece lists and explains four basic tools to strengthen your "psychological immune...

Add a few new titles to your lengthy TBR collection with this Seattle Times interactive. Click one or more of the emotions from the mood bank, and a series of recommended titles and related reviews will pop up for you to peruse (and maybe, one day, read).

The American Psychiatric Association's DSM-5—used for defining diagnoses—says a person must be experiencing five or more symptoms of depression most of the day over at least two weeks. Research indicates older people are less likely than younger people to meet that depression benchmark, though this article says they still often have at least several of the depression symptoms.

The human immune system may become sensitized to pollen and develop an allergic reaction to it after prolonged exposure. Other triggers for new seasonal allergies may include exposure to new environments and changing climate conditions that affect allergy season length and conditions for various pollens.

LSD and psilocybin have shown promise as antidepressants. Using a virtual library of similar chemical compounds, researchers determined via animal studies that two molecules inspired by LSD have antidepressant effects without any associated hallucinogenic experience. These molecules were found to be 40 times more potent than the common antidepressant fluoxetine, also known as Prozac, with antidepressant effects lasting up to 21 days.