A repeating score pattern can help you describe when mood, sleep, appetite, and energy change across the year. It cannot diagnose seasonal affective disorder or prove that daylight caused the change. Diagnosis depends on the symptoms, timing, other episodes, daily function, health history, and a clinical assessment.
A seasonal pattern is more than a hard month
The National Institute of Mental Health describes seasonal affective disorder, or SAD, as depression with a recurrent seasonal pattern. Winter-pattern symptoms usually begin in late fall or early winter. Summer-pattern SAD is less common.
For diagnosis, NIMH says depressive episodes must occur in a specific season for at least two consecutive years. They must also happen more often in that season than at other times. Not everyone with SAD has symptoms every year.
A difficult holiday, work deadline, anniversary, illness, or school term can also return on the calendar. That is why dates alone are weak evidence. Track the event and the symptoms separately.
Winter and summer patterns can look different
Both patterns include depression symptoms. NIMH also lists features that occur more often with each form:
| Winter-pattern features | Summer-pattern features |
|---|---|
| Sleeping more | Trouble sleeping |
| Eating more | Poor appetite |
| Carbohydrate cravings | Weight loss |
| Weight gain | Restlessness or agitation |
| Social withdrawal | Anxiety |
This is not a checklist for self-diagnosis. A person may have some, all, or none of these features. Sleep, appetite, weight, and energy can also change because of medicines, physical illness, stress, pregnancy, substance use, or another mental health condition.
Build a record that preserves context
Use the same questionnaire, version, and language each time. The PHQ-9 records depression symptoms over the previous two weeks. The GAD-7 covers anxiety symptoms over the same period. Neither questionnaire identifies SAD.
Choose a repeat schedule with your clinician or care plan. A monthly PHQ-9 leaves gaps because each result covers only the prior two weeks. More frequent results may overlap. Record the exact date so you know which days each answer describes.
Add a small context log:
| Record | Why it helps |
|---|---|
| Sleep timing and duration | Shows whether sleep changed with mood |
| Appetite and energy | Preserves features a total can hide |
| Daylight or time outdoors | Records exposure without claiming cause |
| Work, school, travel, and holidays | Separates calendar stress from season |
| Illness and medicine changes | Flags other possible explanations |
| Daily function | Shows whether symptoms disrupted life |
Keep the notes brief. A usable record beats a detailed one you stop maintaining.
Read the pattern without naming the cause
Start with observations. For example: “My PHQ-9 totals were higher from November through February in two consecutive years.” That statement stays close to the data.
Then ask what else changed. A winter increase that overlaps with grief, less work, pain, or a medicine change has several possible explanations. A summer increase during heat and poor sleep does too.
A questionnaire score is not a diagnosis. A higher total describes more reported symptoms during its recall period. It does not establish SAD, explain why the change occurred, or show that one treatment caused a later result.
If retirement changed your routine or social contact, compare the calendar record with the retirement tracking guide. Two patterns can overlap.
Bring the record to a clinician
Contact a clinician when symptoms last, return, worsen, or interfere with work, relationships, sleep, or self-care. Do not wait for two full years when you are struggling. The two-year pattern helps with diagnosis; it is not a waiting period for support.
Bring:
- the questionnaire names and dates
- totals and any concerning answers
- the months when symptoms began and eased
- changes in sleep, appetite, energy, and function
- major health, medicine, work, or life changes
Thoughts of suicide or self-harm need prompt support, regardless of the total or season.
If you need help now. In the US, Call 988 or text 988. Call 911 if you are in immediate danger. Outside the US, contact your local emergency number or find support in your country.
Light therapy needs an individual plan
NIMH lists light therapy, psychotherapy, antidepressant medicine, and vitamin D among the treatment categories studied for SAD. The right option depends on the pattern, health history, medicines, preferences, and possible risks.
For winter-pattern SAD, NIMH describes a 10,000-lux light box used for about 30 to 45 minutes, usually in the morning. That is a treatment description, not a personal prescription. Some eye conditions and medicines that increase light sensitivity require medical supervision or a different approach.
Talk with a clinician before starting light therapy or changing medicine or supplements. Bring the product details and your health history. A score cannot screen for light-related risks, bipolar disorder, or medicine interactions.
Start with one honest observation
Record one result, the date, and the context it covers. Repeat the same questionnaire on the agreed schedule. Review the pattern before the season when symptoms usually change.
The useful outcome is not a perfect chart. It is a clear account of what changed, when it changed, how it affected daily life, and which questions still need a clinical answer.