身為一個喜愛戶外耐力運動的醫師,睡眠是訓練中非常重要的一環。大約一年前我和室友討論過『每天該睡多久最有效率』這個問題,搜尋到了一篇 2010 年的經典 Meta-Analysis:
Sleep Duration and All-Cause Mortality: A Systematic Review and Meta-Analysis of Prospective Studies
簡單的結論是,小於 7 個小時及大於 9 個小時的睡眠時間,在統計上被觀察到與較高的死亡率有相關性。然而輪班及值班的工作型態讓我難以持續地達到 7 小時的睡眠目標,直到這個月有較正常的作息與休息時間,運動量及恢復需求也提高後,又讓我重新審視這個問題。因此我利用了 Gemini 的 Deep research 功能,進一步探討人種差異、最佳睡眠時間等,消化後整理出以下資訊(想略過探討可以直接跳到結論):
1. 一般成人睡眠時長建議
多數組織及機構建議睡眠時間應在 7 到 9 小時之間,對年輕的成年人來說,大於 9 個小時的睡眠是否會對健康有負面影響是未知的。
這些組織一致傳達的訊息是,避免短時睡眠(少於 7 小時)至關重要,因為它與廣泛的負面健康結局相關聯,影響層面涵蓋代謝、心血管、心理健康等領域 。
2. U型曲線:睡眠時長對健康的影響
大量的流行病學研究,特別是前瞻性研究的 Meta-Analysis,通常揭示出一種「U型」或「J型」曲線,即過短和過長的睡眠時長都與最佳中間範圍相比風險增加相關。
對全因死亡率的影響: 短睡眠時長(< 7小時)與死亡風險增加 12%相關。相反,長睡眠時長(通常定義為> 9小時)與更顯著的死亡風險增加 30%相關。
對心血管健康的影響(CVD、中風、高血壓): 短睡眠(<7小時)(RR 1.19;95% CI 1.13–1.26)和長睡眠(>9小時)(RR 1.37;95% CI 1.23–1.52)均與心血管疾病死亡風險增加相關,這種U型關聯在亞洲人群和老年個體中可能尤為明顯。
對認知功能的影響:短睡眠(RR 1.34;95% CI 1.15–1.56)和長睡眠(RR 1.21;95% CI 1.06–1.39)均與認知障礙(包括認知衰退、失智症、阿茲海默症和一般認知損害)的發生風險顯著升高相關。
在這些不同的結局中,U型風險曲線的最低點 — — 即風險最低的點 — — 始終出現在大約7–8小時的睡眠時間 。
3. 亞洲人群的特殊考量因素
多項針對或包含人種分析的研究結果,發現當睡眠時長偏離最佳範圍時,亞洲人群可能表現出更顯著的U型風險曲線,尤其是在心血管疾病和死亡率方面。這意味著對於亞洲人而言,維持7–8小時的睡眠區間可能更為重要。
4. 最佳的睡眠時段建議
一項使用英國生物樣本庫 (UK Biobank) 數據的大型前瞻性研究發現,「晚上10:00至10:59之間入睡」與心血管疾病 (CVD) 的最低發病率相關 。
與此最佳時段相比:
- 晚上10:00前入睡,CVD風險增加24%。
- 晚上11:00至11:59之間入睡,風險增加12%。
- 午夜或更晚入睡,風險增加25% 。
即使在校正了睡眠時長、睡眠不規律性及已確立的CVD風險因素後,這種關聯依然存在 。
早於 10:00 入睡及晚於午夜入睡有較顯著(> 20%)的心血管疾病風險升高
5. 個人化建議與結論 – 理想睡眠時段
基於對當前醫學研究,最一致支持的最佳睡眠時長是每晚規律睡眠7至8小時。晚上10:00至10:59之間入睡與心血管疾病 (CVD) 的最低發病率相關 。
個人目標:建立 晚上 11:00 ~ 早上 6:30 的睡眠習慣,維持 7.5 小時睡眠
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