SAD Risk Assessment Calculator

Understanding Seasonal Affective Disorder (SAD)

Seasonal Affective Disorder (SAD) is a pattern of depression that appears at specific times of year, most often in late fall and winter when daylight hours shrink. People with SAD commonly notice a low or "heavy" mood, reduced motivation, increased sleep, and changes in appetite that return toward normal when days get longer again.

This calculator offers an educational way to estimate your risk of experiencing SAD based on self-reported symptoms, your approximate latitude, and how much time you typically spend outdoors. It is not a diagnostic test and cannot replace a conversation with a qualified health professional, but it can help you notice patterns and decide whether to seek further support.

Many people experience some seasonal "winter blues" without meeting criteria for a depressive disorder. This tool is designed to highlight when seasonal patterns and light exposure might be strong enough that a more formal evaluation could be useful.

How the questionnaire works

The five symptom questions are adapted from common SAD and depression screening items. You will be asked about:

• How much your mood tends to drop in late fall and winter
• Whether you crave carbohydrates or heavier foods during darker months
• How strongly you notice low energy with shorter days
• Whether you struggle to wake on dark mornings
• Whether you have ever been diagnosed with depression before

For the first four questions, you choose one of four options: Never, Rarely, Sometimes, or Often. For the question about a previous depression diagnosis, you select Yes or No. The calculator converts each answer into a numerical score and combines them with adjustments for latitude and outdoor time.

To get the most meaningful result, answer based on your typical experience over the last two winters, not just the most recent days or weeks. If your pattern changes a lot from year to year, keep that in mind when interpreting the score.

Scoring model and formulas

The risk estimate is based on a simple additive model. Each response is translated into a number, added together, and then adjusted for light-related factors. Internally, the tool uses the following mapping:

• Moods drop in late fall: Never = 0, Rarely = 1, Sometimes = 2, Often = 3
• Carbohydrate cravings in winter: Never = 0, Rarely = 1, Sometimes = 2, Often = 3
• Low energy with shorter days: Never = 0, Rarely = 1, Sometimes = 2, Often = 3
• Trouble waking on dark mornings: Never = 0, Rarely = 1, Sometimes = 2, Often = 3
• Previous depression diagnosis: No = 0, Yes = 1

The core symptom score adds these values together. Then, the calculator applies two additional adjustments:

• Latitude adjustment (L) – 0 points if your latitude is below 45°, 1 point if it is between 45° and 59.9°, and 2 points if it is 60° or higher.
• Outdoor time adjustment (O) – 0 points if you spend at least 30 minutes outdoors per day on average, and 1 point if you spend less than 30 minutes.

The final risk score S is the sum of your symptom score plus these adjustments. In mathematical form, this can be written as:

Here, r₁ through r₅ represent the scores for each of the five questionnaire items. L is the latitude adjustment, and O is the outdoor time adjustment.

The maximum possible symptom score is 13 (four questions scored 0–3 plus 1 point for a prior depression diagnosis). With the light-related adjustments, the theoretical maximum total score is 16, although most people will fall below that.

Risk bands and interpreting your score

To make the output easier to understand, the calculator groups total scores into broad risk bands:

• 0–3: Lower indicated risk – Your answers suggest relatively few or mild seasonal symptoms. You may still notice some winter dips in energy or mood, but this pattern does not strongly resemble SAD in this simplified model.
• 4–8: Moderate indicated risk – You report several seasonal symptoms or a history of depression, or you live in a region with limited winter daylight and spend little time outside. This pattern is consistent with an increased likelihood of SAD and may warrant closer self-monitoring.
• 9 or higher: Higher indicated risk – Your responses show many of the typical features of SAD, and environmental risk factors may be present. In this band, it is especially reasonable to talk with a health professional about your mood and functioning across seasons.

These ranges are approximate and chosen for clarity rather than as strict clinical cutoffs. A person with a score of 8 is not fundamentally different from someone with a score of 9, and a low score does not guarantee that you will not experience significant seasonal distress.

Example calculation

To see how the model behaves, imagine someone living in a northern city with long, dark winters. They report the following:

• Mood drops in late fall: Often
• Carbohydrate cravings in winter: Sometimes
• Low energy with shorter days: Often
• Trouble waking on dark mornings: Often
• Previous diagnosis of depression: Yes
• Latitude: 52°
• Average outdoor time: 20 minutes per day

Using the scoring rules:

• Mood drop Often = 3
• Carbohydrate cravings Sometimes = 2
• Low energy Often = 3
• Trouble waking Often = 3
• Previous depression Yes = 1

The symptom subtotal is 3 + 2 + 3 + 3 + 1 = 12.

For the adjustments:

• Latitude 52° falls between 45° and 59.9°, so L = 1
• Outdoor time 20 minutes is less than 30 minutes, so O = 1

The final score is S = 12 + 1 + 1 = 14. This falls in the higher indicated risk band. Although this does not establish a diagnosis, it suggests that the person might benefit from discussing winter mood changes with a clinician and exploring strategies such as light therapy, behavioral activation, or adjustments to daily routines.

Latitude, light exposure, and circadian rhythms

Geography and daily light exposure are important pieces of the SAD picture. At around 40° latitude, winter days still offer roughly nine hours of daylight, and the sun reaches a moderate height in the sky. At 60° latitude, winter days can be extremely short, with the sun staying low near the horizon or not rising fully on the darkest days. This extended darkness is linked to stronger shifts in sleep patterns, hormone production, and mood.

The calculator treats latitude in broad bands rather than modeling astronomical details. It assumes that, on average, people at higher latitudes experience more dramatic seasonal light changes and therefore have a greater environmental risk for SAD.

"Circadian rhythms" are your body’s internal 24-hour cycles, which influence when you feel sleepy, alert, hungry, or most focused. Light is the main signal that keeps these rhythms aligned with the outside world. When you get little natural light, especially in the morning, circadian rhythms can drift later, contributing to oversleeping, difficulty waking, and a flattened or depressed mood.

Spending time outdoors, even on cloudy days, exposes you to much brighter light than typical indoor environments. A brief walk near midday or earlier can deliver several times more illuminance than overhead office or home lighting, which is why the calculator includes an adjustment for outdoor minutes.

Comparison of risk bands and next steps

The table below summarizes the three main risk bands, how to interpret them, and potential next steps. These suggestions are general and should not be interpreted as medical directives.

Using your result responsibly

Your score is a starting point for reflection, not a verdict about your mental health. A few ways to make constructive use of the result include:

• Noting whether your symptoms cluster in a specific part of the year
• Thinking about how sleep, activity, and light exposure change across seasons
• Sharing your observations and score range with a healthcare provider as one piece of background information
• Planning small, realistic changes such as brief daily walks in daylight, consistent wake times, or structured social activities in darker months

If your score suggests a moderate or higher indicated risk and you feel that seasonal changes significantly disrupt your life, consider scheduling an appointment with a primary care clinician, psychiatrist, psychologist, or other licensed mental health professional.

Limitations, assumptions, and important disclaimers

This calculator is intentionally simple. It makes several assumptions and has important limitations:

• Not a diagnosis. The tool does not diagnose SAD, major depressive disorder, or any other condition. Only a qualified professional who can evaluate your full history and current situation can make a diagnosis.
• Self-report bias. Results depend entirely on how you answer the questions. People may underreport or overreport symptoms, or may not remember previous seasons accurately.
• Simplified scoring. The symptom weights, latitude bands, and outdoor time threshold are approximate and are not based on a single standardized clinical instrument. They are meant for education, not for clinical decision-making.
• Other causes of symptoms. Low energy, oversleeping, appetite changes, and low mood can result from many medical, psychological, and social factors unrelated to seasons or daylight.
• Latitude and environment. The model uses latitude as a proxy for seasonal light change. Actual light exposure also depends on weather, urban design, work schedules, and cultural habits, which are not captured here.
• Age and health status. The calculator does not adjust for age, physical health conditions, medications, or other mental health diagnoses, all of which can influence how seasons affect mood.

Safety note: If you feel hopeless, cannot carry out daily responsibilities, or have thoughts of harming yourself or others, treat this as an emergency. Contact local emergency services, a crisis hotline, or another urgent resource in your area. Do not rely on an online calculator in a crisis.

By using this tool, you acknowledge that it is provided for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified health provider with any questions you may have about your mental health.