The SAD Episode
In this episode of Stuff You Should Know, hosts Chuck Bryant and Josh Clark examine seasonal affective disorder (SAD), a form of depression that typically occurs during specific seasons. They break down the disorder's symptoms, noting the differences between winter-onset SAD (characterized by oversleeping and increased appetite) and its less common spring/summer variant, while explaining how SAD affects roughly 5% of the U.S. population.
The hosts explore the biological mechanisms behind SAD, including how reduced sunlight affects serotonin production and circadian rhythms. They discuss various risk factors, from geographic location to genetic predisposition, and examine why certain populations—such as women and people living far from the equator—may be more susceptible to developing SAD than others. The episode also addresses how psychological factors and attitudes toward seasonal changes can influence the condition's severity.
This is a preview of the Shortform summary of the Jan 8, 2026 episode of the Stuff You Should Know
Sign up for Shortform to access the whole episode summary along with additional materials like counterarguments and context.
1-Page Summary
Symptoms and Types of Seasonal Affective Disorder
Chuck Bryant and Josh Clark discuss seasonal affective disorder (SAD), a form of depression that typically occurs during specific seasons, most commonly winter. While winter-onset SAD is characterized by oversleeping, increased appetite, weight gain, and social withdrawal, the hosts explain that a less common spring/summer variant exists with opposing symptoms, including insomnia and decreased appetite.
The disorder is classified as major depression with a seasonal pattern, affecting about 5% of the U.S. population. Bryant notes that for a clinical diagnosis, symptoms must appear for at least two consecutive years, though not necessarily every year. Notably, women are four times more likely to develop SAD than men, possibly due to hormonal fluctuations.
Biological Causes of Seasonal Affective Disorder
Clark explains that SAD's biological mechanisms center around serotonin and circadian rhythms. During winter, reduced sunlight leads to lower serotonin production, but unlike in non-SAD individuals, those with SAD don't experience a proportional decrease in serotonin transporters, creating an imbalance that triggers depression.
Bryant cites a 2023 German study showing that seasonal changes affect sleep cycles even with artificial light present. The hosts discuss how decreased winter sunlight increases melatonin production, contributing to lethargy and reduced activity levels, which can worsen SAD symptoms.
Risk Factors and Contributors to Seasonal Affective Disorder
According to Clark, living farther from the equator increases SAD risk due to fewer daylight hours, though Bryant notes some interesting exceptions, such as Trumsa, Norway, where despite two months without sunlight, SAD rates remain surprisingly low.
The hosts discuss genetic factors, explaining that carrying certain variants of the serotonin transporter gene can increase vulnerability to SAD, especially during winter. Additionally, having relatives with SAD or other mood disorders raises one's risk of developing the condition.
Bryant and Clark explore how psychological factors, such as negative attitudes toward winter and anxiety about approaching seasonal changes, can create feedback loops that amplify SAD symptoms. They note that maintaining a positive view of winter activities might help mitigate these effects.
1-Page Summary
Additional Materials
Actionables
- You can create a personalized light therapy routine by setting up a bright light station in your home where you spend 20-30 minutes each morning. Position a full-spectrum light box at your breakfast table or desk to simulate sunrise, helping to reset your circadian rhythm and combat the effects of reduced winter sunlight.
- Develop a winter-positive mindset by starting a winter journal where you list daily activities or aspects of the season you enjoy. This could be anything from the taste of hot cocoa to the sound of crunching snow underfoot. By focusing on positive winter experiences, you may help mitigate the psychological impact of negative attitudes toward the season.
- Engage in a 'virtual travel' experience by using a projector or large screen to display summery scenes in your living space for an hour each evening. Choose videos or live streams from sunny locations around the world to create a temporary escape from the winter gloom, potentially easing the longing for sunlight and improving your mood.
Get access to the context and additional materials
Symptoms and Types of Seasonal Affective Disorder
Seasonal Affective Disorder Involves Depression During Specific Times, Usually Winter
Seasonal affective disorder (SAD) is a depressive condition tied to seasons, typically manifesting in winter, though it can also occur in summer. Chuck Bryant and Josh Clark discuss how SAD often begins in the fall or early winter and tends to subside when spring arrives. When symptoms persist for days, particularly during winter, it may be a sign to consult a medical professional.
Symptoms of Winter-Onset SAD: Oversleeping, Increased Appetite, Weight Gain, Low Energy, Fatigue, Social Withdrawal
Winter-onset SAD, which is more common, includes symptoms such as oversleeping, craving for carbohydrates, overeating, weight gain, fatigue, low energy, and social withdrawal. These symptoms can create a feedback loop exacerbating depression.
Depression in Spring/Summer: Symptoms Include Insomnia, Decreased Appetite, Weight Loss, Irritability
The less common spring and summer variant of SAD includes symptoms opposite to those of winter SAD, such as trouble sleeping (insomnia), reduced appetite, weight loss, and feelings of anxiety, agitation, and irritability. Clark suggests that the increase in energy during these warmer seasons may be related to a higher incidence of suicide in spring and summer.
SAD Is Major Depression With a Seasonal Pattern
SAD Symptoms May Recur Annually, but Not Every Year
SAD is identified in the DSM as a major depressive disorder with a seasonal pattern. While about 5% of the U.S. population experiences severe depressive symptoms in the winter months due to SAD, Brya ...
Here’s what you’ll find in our full summary
Symptoms and Types of Seasonal Affective Disorder
Additional Materials
Counterarguments
- The prevalence rate of SAD might vary based on different studies or populations, and the 5% figure could be specific to certain regions or demographics.
- While women are reported to be more likely to develop SAD, the gender disparity in diagnosis could be influenced by social factors, such as men being less likely to seek help for depressive symptoms.
- The hormonal explanation for the higher incidence of SAD in women is one theory, but other factors such as psychosocial stressors and genetic predispositions could also play significant roles.
- The link between increased energy in spring and summer and higher suicide rates is complex and may involve multiple factors beyond seasonal changes, such as psychosocial and environmental factors.
- The assertion that symptoms must be present for at least two consecutive years for a diagnosis of SAD could be interpreted as too rigid, potentially overlooking those who experience significant distress during one season.
- The idea that SAD sympto ...
Actionables
- Track your mood and energy levels with a simple journal to identify patterns that may indicate SAD. By noting daily entries on your mood, sleep quality, energy levels, and diet, you can spot trends that align with seasonal changes. For example, you might notice a consistent drop in mood and energy as the days shorten in the fall, which could prompt you to seek further support or interventions.
- Create a personalized light environment at home to counteract the effects of reduced daylight. Invest in a light therapy lamp and use it for 20-30 minutes each morning during the fall and winter months. Additionally, arrange your living and workspaces to maximize natural light exposure, such as positioning your desk near a window or using mirrors to reflect daylight into darker areas of your home.
- Develop a seasonal wellness plan that includes diet, exercise, and social activities tailored to your needs. For winter, this might involve scheduling regular indo ...
Get access to the context and additional materials
Biological Causes of Seasonal Affective Disorder
The biological underpinnings: of Seasonal Affective Disorder (SAD) are multi-faceted, with serotonin and circadian rhythms playing significant roles in its development.
Serotonin Levels and Transporter Function Variations Are Key In SAD
Serotonin Drops in Winter For SAD, but Transporters Don't Decrease Proportionally
SSRIs, a treatment for SAD, target serotonin levels, highlighting serotonin's role in the disorder. Josh Clark explains that sunlight boosts serotonin production, and thus, lower winter sunlight leads to decreased serotonin levels. In most individuals, serotonin transporters decrease in winter to help maintain mood; however, this adjustment is ineffective in those with SAD.
This Creates an Imbalance That Can Trigger Depression
People with seasonal affective disorder maintain stable serotonin levels throughout the year, but during winter, these levels drop without a proportional decrease in serotonin transporter proteins. This results in serotonin being removed more quickly than it should be, leading to depressive symptoms associated with Seasonal Affective Disorder.
Circadian Rhythm Disruptions and Melatonin Affect SAD
Suprachiasmatic Nucleus Regulates Circadian Rhythms Influenced by Light
The suprachiasmatic nucleus (SCN), located in the hypothalamus, plays a crucial role in regulating circadian rhythms, which are influenced by light exposure. Melatonin production is triggered when sunlight hits the retinas and sends signals to the SCN. This process subsequently influences the pineal gland, based on environmental cues, especially light.
Winter's Decreased Light Raises Melatonin, Disrupts Sleep, Worsens Sad
A 2023 German study cited by Chuck Bryant found that sleep cycles change with seasons even under ar ...
Here’s what you’ll find in our full summary
Biological Causes of Seasonal Affective Disorder
Additional Materials
Counterarguments
- The role of serotonin in SAD is complex, and while SSRIs can be effective, not all patients respond to them, suggesting that other neurotransmitters or mechanisms may also be involved.
- The relationship between serotonin levels and mood is not fully understood, and some research suggests that the cause of depression (including SAD) may not be as simple as a deficiency in serotonin.
- The text implies a direct causation between light exposure, serotonin, and melatonin levels, but individual responses to light and the development of SAD symptoms can vary greatly, indicating that other factors may contribute to the disorder.
- The effectiveness of bright light therapy and dawn simulation devices can vary among individuals, and while they are helpful for some, they may not be universally effective for all SAD sufferers.
- The text does not address the potential impact of lifestyle, diet, exercise, and social factors on SAD, which can also play significant roles in its development and management.
- The text does not consider genetic predispositions to SAD, which can influence how individuals respond to changes in season and light exposure.
- The text does not discuss the potential side effects or limitations of treatments like SSRIs and li ...
Actionables
- You can create a personalized light exposure schedule to optimize serotonin levels by tracking your daily exposure to natural light and adjusting your routine to increase it, especially in the morning. For example, take a short walk outside shortly after waking up or arrange your workspace to receive more daylight.
- Experiment with scent therapy using essential oils that are known to influence serotonin levels, like lemon or bergamot, by diffusing them in your living space during the darker months to potentially enhance mood and counteract the effects of SAD.
- Develop a sleep-wake rhythm that aligns more closely with na ...
Get access to the context and additional materials
Risk Factors and Contributors to Seasonal Affective Disorder
Josh Clark and Chuck Bryant delve into the risk factors and contributors to Seasonal Affective Disorder (SAD), considering both genetic and environmental aspects as well as the psychological response to seasonal changes.
Distance From the Equator Raises SAD Risk
Fewer Daylight Hours Increase Winter SAD Rates
Clark mentions that being further from the equator, and hence at a higher latitude, raises the likelihood of having seasonal affective disorder due to fewer daylight hours. Particularly in places far from the equator or in locales like Seattle, which experiences a high number of gray days, people are more susceptible to SAD.
Bryant discusses the findings of a meta-analysis showing that with each one-degree increase in latitude, which results in fewer daylight hours, the rates of Winter SAD increase. An interesting counterpoint is brought up with the example of Trumsa, Norway—a northern city with no sunlight for two full months—and yet, its inhabitants have much lower rates of SAD than might be expected.
Serotonin Transporter Gene Variants' Role in SAD Predisposition
The hosts discuss the genetic linkage to SAD, noting that having family members with depression or other mental health disorders may raise the risk of developing seasonal affective disorder. Specifically, individuals carrying at least one short allele in the serotonin transporter gene promoter region tend to be more vulnerable to depression. During winter, heightened levels of serotonin transporters are associated with this genetic variant, subsequently increasing the risk of SAD.
Close Relative With SAD or Mood Disorder Increases Risk
Having a close relative with SAD or another mood disorder significantly raises the likelihood of one developing SAD, highlighting the hereditary component of this condition.
Psychological and Environmental Factors Amplify SAD Symptoms
Winter Negativity and Activity Lack Worsen Condition
Bryant remarks that general feelings of negativity during winter reflect a broader psychological tendency that can amplify SAD symptoms. Clark suggests that this negativeness may ...
Here’s what you’ll find in our full summary
Risk Factors and Contributors to Seasonal Affective Disorder
Additional Materials
Counterarguments
- While latitude and daylight hours are correlated with SAD, individual sensitivity to light varies, and not everyone at higher latitudes experiences SAD.
- The lower rates of SAD in places like Tromsø could be due to a variety of unexplored factors, such as cultural attitudes toward winter, community support, or adaptation strategies that mitigate the impact of darkness.
- Genetic predisposition does not guarantee the development of SAD; environmental factors and personal history also play significant roles.
- The role of the serotonin transporter gene in SAD is complex, and carrying the short allele is not the sole determinant of SAD risk.
- The assertion that negativity during winter is an evolutionary remnant is speculative and may not account for individual or cultural differences in winter experiences.
- While CBT can be effective for some individuals, it may not work for everyone, and other ...
Actionables
- You can create a personalized 'winter toolkit' with items that stimulate positive emotions and sensory experiences to combat negative winter perceptions. Fill a box with things like scented candles that remind you of summer, a playlist of upbeat music, photos from sunny vacations, or a soft blanket that feels comforting. When you notice negative thoughts about winter creeping in, open your toolkit and engage with the items to shift your mood.
- Develop a 'winter hobby project' that you'll only work on during the colder months to foster a sense of excitement and purpose. This could be anything from learning to knit, starting an indoor herb garden, or building a model ship. The key is to choose something that feels rewarding and can be done comfortably inside, making you look forward to rather than dread the winter season.
- Organize a 'positive winter challenge' w ...
Get access to the context and additional materials
Create Summaries for anything on the web
Download the Shortform Chrome extension for your browser
