一到冬季就"抑鬱"?
一場大雪讓很多北方城市都提前進入冬季。因爲天氣寒冷，很多人都願意宅在家裏，還有人會因爲晝短夜長而有些情緒波動。這個冬季，你憂鬱了嗎？
Seasonal affective disorder (SAD) is a type of depression that sets in or starts in the winter months. Unlike other types of depression, it may improve as spring comes on. It is often a cyclical, recurring disorder--you'll feel depression every winter and begin to feel better each spring.
季節性情緒紊亂（seasonal affective disorder，SAD）指多發於冬季的一種抑鬱症，也稱“冬季抑鬱症”。與其它類型的抑鬱症不同的是，這種季節性抑鬱症會在春天到來時有所好轉。這是一種循環的、反覆發生的情緒紊亂，每年冬天時覺得抑鬱，春天到來時又好轉了。A study by Alfred Lewy at the Oregon Health and Science University found that most of the symptoms of seasonal affective disorder are caused by body rhythms that are not in sync with the sun. Often the body gets out of sync with the sun because of winter's shortened days. The pineal gland, which regulates body rhythms, secretes a hormone called melatonin during the night. This can affect your sleep wake cycle and other rhythms. When it gets dark too early in the day, the pineal gland and the body's sleep wake cycle get out of sync.
俄勒岡健康與科學大學的阿爾弗雷德?洛威所做的一項研究發現，季節性情緒紊亂的大部分症狀是由身體節律與太陽不同步導致的。通常來說，身體會因爲冬季白天變短而無法與太陽同步。控制身體節律的松果體會在夜間分泌一種叫做褪黑素的激素。這種激素會影響你的作息週期和其它節律。天黑得太早時，松果體和身體的作息週期就無法同步。Seasonal affective disorder is far more common in northern climates, where days can be very short in winter. SAD affects more women than men and is likelier to occur in people under age 40 than those older than that.
季節性情緒紊亂在北方氣候地區更常見，北方冬季的白天都很短。該症狀的女性患者多於男性，而且更易發生在40歲以下人羣中。
