【醫學知識：季節性憂鬱症 (SAD)：當季節影響心理健康之研究 / 李霸】

thechicagochinesenews

4 months ago

季節性憂鬱症是一種具有可預測季節規律的抑鬱症形式。它的英文名稱「Seasonal Affective Disorder」縮寫為 SAD，這對許多人來說幾乎是一個令人隱隱作痛的貼切巧合——這個縮寫精確地捕捉到了患者的真實感受：悲傷（Sad）。

對大多數人而言，症狀始於秋季或初冬，在最黑暗的月份裡加劇，並隨著春季白天變長而緩解。較少見的情況是，有些人會經歷相反的模式：症狀在春末或夏季出現，並在秋季消失。

雖然許多人隨口將其稱為「冬季憂鬱」（winter blues），但 SAD 並非只是對寒冷天氣的輕微或純心理反應。它在臨床上被定義為**重度抑鬱症（Major Depressive Disorder）**的一個亞型，與可測量的生物學變化和日常功能的顯著受損密切相關。

辨識模式

許多患者在聽說這個術語之前，就已經察覺到了這種規律。

一位研究生告訴我，每年 11 月，她的動力都會毫無例外地崩潰。「我開始睡過頭、錯過鬧鐘，郵件堆積如山，我一直感到內疚——但我並不覺得自己懶惰，我只是覺得『卡住了』。」到了 4 月，她又恢復了自我，甚至對冬天對她影響之深感到困惑。

另一位中年專業人士描述了所謂的「一月迷霧」。「我停止運動、不再打電話給朋友，並深信自己工作表現很差——儘管什麼都沒有改變。」多年來，他一直認為這是性格缺陷，而非一種可以治療的疾病。

這種可預測性——症狀隨季節可靠地出現，並隨日照增加而緩解——是診斷季節性憂鬱症最重要的線索之一。

DSM-5 中的季節性憂鬱症

在《精神疾病診斷與統計手冊》第五版（DSM-5）中，季節性憂鬱症並未列為獨立診斷。相反，它被診斷為**「重度抑鬱症，反復發作，伴有季節性模式」**，或在某些情況下診斷為「雙相情緒障礙症（躁鬱症），伴有季節性模式」。

DSM-5 規定了季節性模式的幾項標準：

抑鬱發作的開始與一年中特定時間之間存在規律的時間關係。
在一年中的特徵性時間完全緩解（或轉向躁狂/輕躁狂）。
至少連續兩年觀察到此模式，且期間未出現非季節性的抑鬱發作。
在個人一生中，季節性發作次數多於非季節性發作。

我經常向患者解釋，這個診斷與其說是在於嚴重程度，不如說是在於可靠性。如果抑鬱症是按照日曆時間表到來和離開的，這項資訊至關重要——它可以引導出更有力的治療方式。

誰會受到影響？

在美國，季節性憂鬱症影響約 5% 的成年人，另有 10% 到 20% 的人會經歷較輕微、但仍干擾生活的季節性情緒變化。女性的診斷率高於男性，且通常始於成年早期，儘管也可能更早出現。

地理位置也扮演了重要角色：居住在遠離赤道、冬季日照有限地區的人風險較高。一位從南加州搬到太平洋西北地區的患者描述自己被第一個冬天「偷襲」了。「我一直在等待適應，」她告訴我，「結果我只是變得越來越難過。」她的症狀在次年春天幾乎完全消失。家族抑鬱症或躁鬱症史，以及個人的情緒障礙史，也會增加風險。

SAD 的日常生活感受

由於 SAD 是重度抑鬱症的一種，其症狀與廣義的抑鬱症重疊，但通常帶有獨特的季節性特徵。常見症狀包括：

持續的情緒低落或悲傷
對活動失去興趣或樂趣
精力不足和身體沉重感
難以集中注意力或清晰思考
睡眠時間增加且起床困難
食慾增加，特別是渴望碳水化合物
體重增加
社交退縮
絕望感、內疚感或無價值感

許多患者描述的不僅是情感上的痛苦，還有一種身體上的**「減速感」**。有人告訴我：「感覺就像我的大腦切換到了省電模式。」認知症狀尤為常見，人們經常報告腦霧、健忘或找不出詞彙——如果他們沒意識到抑鬱症會影響認知功能，這些症狀可能會令人感到恐懼。

冬季型與夏季型 SAD

冬季型 SAD：最常見的形式，表現為嗜睡、食慾增加、體重增加和精力低落。
夏季型 SAD：較罕見，傾向於表現為失眠、焦慮、易怒、食慾下降和體重減輕。在這些案例中，高溫和生理時鐘紊亂的影響可能大於缺乏光照。

為什麼光照如此重要？

最強有力的證據表明，SAD 主要是由自然光暴露減少驅動的。陽光調節大腦的晝夜節律（Circadian Rhythm），即控制睡眠、荷爾蒙釋放、警覺性和情緒的生理時鐘。當白天縮短時，這個節律可能會失調。

陽光還會影響血清素（調節情緒的神經傳導物質）和褪黑激素（促進睡眠的荷爾蒙）。在冬季，血清素活性可能下降，而褪黑激素水平上升，導致疲勞、情緒低落和過度嗜睡。我常向患者解釋，他們的大腦正對黑暗做出適當的反應——但在一個要求全年產出的現代世界中，這種反應就成了一個問題。

有效的治療方法

季節性憂鬱症具有高度可治療性，許多患者的反應比非季節性抑鬱症更快且更顯著。

1. 光照治療（Light Therapy）

這是冬季型 SAD 的首選治療方法。它涉及每天暴露在強烈的人造光下（通常為 10,000 勒克斯），以模擬自然陽光。大多數人每天早晨使用光照盒 15 到 30 分鐘。一位患者將其描述為「給大腦一個偽裝的日出」。臨床研究顯示，50% 到 80% 的患者症狀有所改善。

2. 抗抑鬱藥物

常見的選擇包括選擇性血清素再攝取抑制劑（SSRIs），如百憂解（Prozac）、左洛復（Zoloft）和立普能（Lexapro）。威博雋（Wellbutrin）也常用於預防性治療。

3. 心理治療

**認知行為治療（CBT）**對 SAD 特別有效。它幫助患者識別季節性的負面思維模式，減少逃避行為，並在冬季維持有意義的例行生活。

日常生活的支持策略

在白天多花時間進行戶外活動
定期運動
維持規律的睡眠時間
增加室內照明
即使缺乏動力，也要保持社交聯繫

何時尋求幫助

季節性的情緒波動很常見。但如果症狀持續數週、損害了社交或工作功能，或者每年固定時間復發，就應該進行專業評估。任何關於死亡或自殺的想法都需要立即關注。在美國，可以撥打自殺與危機熱線（988）。

結語

季節性憂鬱症或許名副其實（SAD），但人們不需要在沉默中忍受。它是真實的、受生物因素影響的，且對治療反應良好。透過辨識、計劃和正確的干預，冬天不一定意味著數月的痛苦。對許多患者來說，理解這個規律是奪回季節——以及找回自我——的第一步。

Seasonal Affective Disorder (SAD): When the Seasons Affect Mental Health / By Dr. Bob Lee, DO, MS, MBA.

Seasonal affective disorder is a form of depression marked by a predictable seasonal pattern. The name is almost painfully appropriate. Seasonal affective disorder is commonly abbreviated as SAD, and for many people, that acronym captures the experience exactly. For most individuals, symptoms begin in the fall or early winter, intensify during the darkest months, and then ease with the return of longer days in spring. Less commonly, some people experience the opposite pattern, with symptoms emerging in late spring or summer and resolving in the fall.

Although many people casually refer to this as the “winter blues,” SAD is not a mild or purely psychological reaction to cold weather. It is a clinically defined subtype of major depressive disorder, associated with measurable biological changes and meaningful impairment in daily functioning.

Recognizing the Pattern
Many patients recognize seasonal affective disorder long before they ever hear the term.

One graduate student told me that every November, without fail, her motivation collapsed. “I start sleeping through alarms, my emails pile up, and I feel guilty all the time – but I don’t feel lazy. I feel stuck.” By April, she felt like herself again, almost bewildered that winter had affected her so deeply. Another patient, a middle-aged professional, described what he called his “January fog.” “I stop exercising, stop calling friends, and I’m convinced I’m bad at my job – even though nothing has changed.” He had assumed this was a character flaw for years, not a treatable condition.

That predictability – the way symptoms reliably return with the seasons and remit when daylight increases – is one of the most important clues that seasonal affective disorder may be present.

Seasonal Affective Disorder in the DSM-5
In the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), seasonal affective disorder is not listed as a standalone diagnosis. Instead, it is diagnosed as major depressive disorder, recurrent, with seasonal pattern, or, in some cases, bipolar disorder with seasonal pattern.

The DSM-5 specifies several criteria for the seasonal pattern specifier:

A regular temporal relationship between the onset of depressive episodes and a particular time of year.

Full remission, or a switch to mania or hypomania, at a characteristic time of year.

At least two consecutive years in which this pattern is observed, without nonseasonal depressive episodes during that period.

Seasonal episodes outnumber nonseasonal episodes over the individual’s lifetime.

I often explain to patients that this diagnosis is less about severity and more about reliability. If depression arrives and leaves on a calendar schedule, that information matters – and it can guide treatment in powerful ways.

Who Is Affected?

Seasonal affective disorder affects approximately 5% of adults in the United States, with another 10% to 20% experiencing milder seasonal mood changes that still interfere with daily life. It is diagnosed more frequently in women than men and typically begins in young adulthood, though it can appear earlier. Geography also plays a role: people who live farther from the equator, where winter daylight is limited, are at higher risk. One patient who relocated from Southern California to the Pacific Northwest described feeling blindsided by her first winter. “I kept waiting to adjust,” she told me. “Instead, I just kept getting sadder.” Her symptoms resolved almost completely the following spring. Family history of depression or bipolar disorder also increases risk, as does a personal history of mood disorders.

What SAD Feels Like Day to Day
Because seasonal affective disorder is a subtype of major depressive disorder, its symptoms overlap with depression more broadly, but often with a distinctive seasonal signature.

Common symptoms include:

Persistent low mood or sadness

Loss of interest or pleasure in activities

Low energy and physical heaviness

Difficulty concentrating or thinking clearly

Increased sleep and difficulty waking

Increased appetite, especially carbohydrate cravings

Weight gain

Social withdrawal

Feelings of hopelessness, guilt, or worthlessness

Many patients describe not just emotional pain, but a bodily sense of slowing down. One person told me, “It feels like my brain switches to power-saving mode.” Cognitive symptoms are especially common. People often report brain fog, forgetfulness, or trouble finding words – symptoms that can be frightening if they don’t realize depression can affect cognition.

Winter-Onset vs. Summer-Onset SAD
Winter-onset SAD is by far the most common form and is associated with hypersomnia, increased appetite, weight gain, and low energy.

Summer-onset SAD, which is much rarer, tends to present with insomnia, agitation, anxiety, irritability, decreased appetite, and weight loss. In these cases, heat and circadian disruption may play a larger role than light deprivation alone.

Why Light Matters So Much
The strongest evidence suggests that seasonal affective disorder is driven primarily by reduced exposure to natural light. Sunlight regulates the brain’s circadian rhythm, the internal clock that controls sleep, hormone release, alertness, and mood. When daylight shortens, this rhythm can become misaligned. Sunlight also affects serotonin, a neurotransmitter involved in mood regulation, and melatonin, a hormone that promotes sleep. In winter, serotonin activity may decrease while melatonin levels rise, leading to fatigue, low mood, and excessive sleepiness. I often explain to patients that their brains are responding appropriately to darkness – but in a modern world that expects year-round productivity, that response becomes a problem.

Treatment That Works
Seasonal affective disorder is highly treatable, and many patients respond more quickly and robustly than they do with nonseasonal depression.

Light Therapy
Light therapy is often the first-line treatment for winter-onset SAD. It involves daily exposure to bright artificial light, typically 10,000 lux, which mimics natural sunlight. Most people use a light box for 15 to 30 minutes each morning, ideally before 10 a.m. The light is positioned off to the side, allowing people to read or eat while using it. One patient described light therapy as “giving my brain a fake sunrise.” Within two weeks, her energy and motivation began to return.

Clinical studies show improvement in 50% to 80% of patients. Side effects are usually mild and transient, though people with bipolar disorder or certain eye conditions should use light therapy under medical guidance.

Antidepressant Medications
Antidepressants are another effective option. The most commonly prescribed class is selective serotonin reuptake inhibitors (SSRIs), which increase serotonin availability in the brain. Examples include Prozac (fluoxetine), Zoloft (sertraline), and Lexapro (escitalopram). Wellbutrin (bupropion), an antidepressant that affects dopamine and norepinephrine, is also commonly used and may be started preventively in the fall for individuals with a clear seasonal pattern.

Psychotherapy
Cognitive behavioral therapy (CBT) is particularly effective for SAD. It helps patients identify seasonal negative thought patterns, reduce avoidance, and maintain meaningful routines during winter months. One patient told me that CBT helped her stop “waiting for spring to live again.”

Supporting Recovery Outside the Clinic
Lifestyle strategies can significantly enhance treatment:

Spending time outdoors during daylight hours

Exercising regularly

Maintaining consistent sleep schedules

Increasing indoor lighting

Staying socially connected, even when motivation is low

Isolation often worsens seasonal depression. Small, intentional connections can be protective, even when energy is limited.

When to Seek Help
Seasonal mood changes are common. But if symptoms last weeks, impair functioning, or recur at the same time each year, professional evaluation is warranted. Mental health diagnoses always require a professional evaluation by a physician – such as a psychiatrist, a mental health specialist. Any thoughts of death or suicide require immediate attention. In the United States, the Suicide and Crisis Lifeline (988) is available 24 hours a day.

Closing Thoughts
Seasonal affective disorder may live up to its acronym, but it is not something people need to endure in silence. SAD is real, biologically influenced, and highly responsive to treatment. With recognition, planning, and the right interventions, winter does not have to mean months of suffering. For many patients, understanding the pattern is the first step toward reclaiming the season – and themselves.