SAD 101 from the folks at NIMH—where the condition was first identified

Read Norman Rosenthal’s original 1984 paper describing 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’s struggle with SAD inspired him to understand it

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.

Roughly 10% of the world has SSAD—SAD’s milder, nonclinical cousin

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.

Its predictability distinguishes SAD from other forms of depression

Most major depression is "stochastic"—brought on without a clear trigger. SAD—also known as major depression with a seasonal component—is unique in that its onset is predictable. Many of those affected can predict its occurrence accurately within a range of three weeks. This podcast explores this unusual feature of SAD, among other expert takes.

10 percent of SAD cases occur in the summer

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.

One theory claims the retinae of SAD patients may fail to adjust to less light in winter

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.

Winter-risk SAD is more likely in regions above 40 degrees latitude north

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.

An engineer tracked his moods for decades and helped researchers identify SAD

Civil engineer Herb Kern had bipolar and would record his moods dating back to 1967. He noticed the seasons were a major factor in the increase and severity of his episodes. By reaching out to researchers at the National Institute of Mental Health, Kern became the first human to confirm increased melatonin levels during winter and to receive bright light therapy.

SAD disrupts melatonin secretion, producing it longer in the morning

The hormone is secreted from the pineal gland in the brain and is key to the timing of sleep. However, the substance does not generate sleep itself. With seasonal affective disorder, the body misperceives the photoperiod—the time with light—and the cycle of sleeping and waking gets off-phase, leading to issues with circadian rhythms.

The science of springtime, 101

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.

Explore this deep dive into how SSRIs work

This 101-style explainer on selective serotonin reuptake inhibitors explains how they work in the brain—complete with classroom-style whiteboard drawings. It covers common SSRIs, why someone might try this medication, and a deeper discussion about potential side effects.

How depression affects the brain

Treatment for depression has historically hinged on the theory that the condition was caused by underactive or abnormal neurotransmitters, specifically serotonin and norepinephrine. This four-minute video by Yale Medicine details how these neurotransmitters didn't explain the symptoms of depression but, two other neurotransmitters involved in regulating mood and emotion did. GABA and glutamate, some of the brain's most plentiful neurotransmitters, may possibly be the source of depressive symptoms.

Migrane 101: data, symptoms, and treatments

Living with migraine, however often the neurological condition attacks, is a journey fraught with pain and isolation. This migraine guide offers insight into the condition, common triggers, possible treatments, personal stories, and tips for managing life with migraine.

Why we don't have an answer for the common cold

Since a landmark study of the common cold in 1925, researchers have learned much more about the seasonal ailment. Despite continuous study, people still contract colds for similar periods of time at the same rate with the same symptoms, and there's no vaccine. This article explains how the many viral strains make it hard to control.

The psychology of narcissism

It's not just an insult: Narcissistic personality disorder impacts thousands of people—and there are ways to get better. Here's a short video explaining it.

Visualizing where happiness comes from

Researchers asked 10,000 participants to list 10 things that recently made them happy. One author broke down the responses into subject-verb-object categories, isolating the people and events that made responders satisfied. The result highlights how simple things like having dinner or watching a movie made someone happy. Dive in and look for some ideas or tips on feeling happy today with this fascinating visualization.

See this collection of mental health cartoons

These cartoons were curated around mental health themes in celebration of World Mental Health Day, which is observed annually on Oct. 10. The 15+ cartoons include thematic nods to weathering mental health challenges and looking forward to better times ahead.

The science of addiction treatment

A helpful resource from the National Institute on Drug Abuse (part of the NIH). This article examines addiction treatment and recovery through the science behind several accepted methods. The guide draws helpful comparisons with other chronic disease treatments. In particular, it discusses the overlap between medications and therapeutic treatments, and the understanding that relapse doesn’t indicate treatment failure—only a need for continued or modified care.

Could all mental health disorders have a unifying 'p-factor'?

Some researchers have argued in the past couple decades that all mental health disorders may have a unifying dimension—a theoretical "p-factor" that is common across mental illness, but life experiences and behaviors influence if and how illness manifests. Proponents point to similarities across different disorders, while detractors argue that such connections are largely exaggerated.

How did the pandemic affect mental health?

Read this research brief to learn more about why heightened mental health and substance use concerns persist three years after the outbreak of COVID-19. According to a recent survey, the vast majority of American adults view the nation as facing a...

Diagnosis as an adult can have huge benefits, including helping someone with ASD to feel real

This first-person account of a woman diagnosed with autism at age 31 covers her experience of why it was useful for her to receive her diagnosis as an adult and how it helped her to understand her life and her feelings of 'being an imposter.'

The deadly genetic disease that steals shut-eye

Few are haunted by fatal familial insomnia. This neurodegenerative disease is typically carried through bloodlines via genetic mutation of the prion protein gene, forcing the body to create abnormal and pathological protein variations that can corrupt normal versions. This article follows a musician as they attempt to come to terms with the FFI plaguing their family (and, possibly, their future).

Aphantasia involves a lack of mental images—but doesn't affect behavior

The condition, generally known about for over a century, first received its name in 2015 by researcher Adam Zeman. An estimated 4% of people lack this ability to perceive mental images, and research suggests this deficiency does not have any practical impact on behavior.

HFMD was first reported in 1957 in New Zealand

The first clinical report involved eight kids with the characteristic sores in New Zealand, and then in the years that followed there were dozens more cases there and also reports of outbreaks in England and Scotland, among other settings, including the US.

Emotional crying is an important and cathartic process

Though babies don't initially produce tears when they cry, this podcast discusses how humans are hardwired to cry throughout life. Most crying research relies on self-reporting of crying and emotions. This podcast notes that there aren't neuroimaging studies of crying—they're quite expensive to complete. As a result, the brain precursors and processes during a bout of crying remain understudied.

In recent years a child anxiety expert has created and tested a novel phobia and anxiety treatment approach for children, focused on changing how parents respond to the fears.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Explore an interactive map built from more than 100,000 survey responses on where people find joy in their lives

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

This real-time tracking of the hantavirus cruise ship outbreak in May 2026 offers a unique glimpse into the global reach of the outbreak and whether the virus sickened passengers and their communities around the world.

The 19th-century painters of the Hudson River School were among the first American romantics, with portraits that displayed the natural beauty of the young country.

Poison ivy can cause rashes year-round since all parts of the plant contain urushiol, the oil that triggers our allergic response.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

El Niño, Spanish for 'the boy,' was named after Jesus Christ because the phenomenon resembled the weather changes observed around Christmastime.

Explore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

A century of Billboard issues documenting the evolution of popular music.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

The first horror movie is believed to be George Méliès' 1986 short 'The Haunted Castle,' which pioneered the use of special effects

View the ten deadliest tornadoes in US history.

Learn how monoclonal antibodies, which mimic the body's antibodies, can fight diseases like Ebola.

A researcher recently discovered an interview from 1967 between groundbreaking journalist Joan Didion and the Grateful Dead, years before the band became an institution.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

Up to a million Girl Scouts sell about 200 million cookie boxes every spring, generating $800 million, largely because refusing a child is frowned upon

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.