“睡前喝牛奶有助睡眠”的說法由來已久。為了改善睡眠狀況，不少人都有睡前喝熱牛奶的習慣。但喝牛奶真的能讓我們睡得更好嗎？牛奶助眠是一種心理安慰，還是有科學依據？我們來一起探究牛奶與睡眠的關係吧。
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May help some people fall asleep faster
喝牛奶可能讓一部分人更快入睡
A handful of small animal and human studies demonstrate that consuming dairy products like milk and cheese before bed may help some people have a more restful night’s sleep, though the reason why remains unclear.
一些對小動物和人類的研究表明，睡前飲用牛奶和食用乳酪等乳製品可以幫助一些人睡得更安穩，但原因尚不清楚。
Most experts agree that milk’s sleep-promoting potential is likely related to specific chemical compounds or the psychological effects of having a soothing bedtime routine — or perhaps a combination of the two.大多數專家認為，牛奶促進睡眠可能與某些化學物質有關，也可能與這一放鬆的睡前習慣所產生的的心理效應有關，或者兩者兼而有之。
May promote healthy sleep cycles
促進健康的睡眠週期
Certain compounds in milk — specifically tryptophan and melatonin — may help you fall asleep.
牛奶中的某些化合物，特別是色氨酸和褪黑素可以幫助你入睡。
Tryptophan is an amino acid found in a variety of protein-containing foods. It plays an important role in the production of the neurotransmitter known as serotonin .
色氨酸是一種氨基酸，存在於多種含蛋白質的食物中。它對合成神經遞質5-羥色胺起著重要作用。
Serotonin boosts mood, promotes relaxation, and functions as a precursor in the production of the hormone melatonin.
5-羥色胺能改善情緒，有助於放鬆，是褪黑素產生的前體。
Note:
melatonin n. 褪黑素
Melatonin, also known as the sleep hormone, is released by your brain. It helps regulate your circadian rhythm and prepare your body for entering a sleep cycle.
褪黑素，也稱為睡眠激素，由大腦釋放。它有助於調節晝夜節律，讓你的身體為進入睡眠週期做好準備。
Note:
circadian adj. 晝夜節律的，生理節奏的
The role of tryptophan and melatonin in sleep disorders is well established, and studies have found that taking supplements of these compounds may improve sleep and reduce symptoms of anxiety and depression that can crop up at bedtime.
色氨酸和褪黑素在治療睡眠障礙中的作用已得到證實，研究發現，補充這些化合物可以改善睡眠，減少睡前可能出現的焦慮和抑鬱症狀。
Note:
crop up（尤指意外地）出現，發生
However, there’s currently no evidence to suggest that a single glass of milk contains enough tryptophan or melatonin to significantly influence your body’s natural production of melatonin or to independently treat a disordered sleeping pattern.
然而，目前沒有證據表明一杯牛奶中含有足夠的色氨酸或褪黑素，可以顯著影響身體褪黑素的自然生成，或者獨立治療睡眠紊亂。
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Psychological effects
心理效應
Some experts suspect that milk’s potential role as a sleep aid has little to do with its nutritional profile and that it’s instead more closely related to the psychological effect of having a calming bedtime ritual.
一些專家懷疑，牛奶作為助眠劑的潛在作用與其營養成分無關，相反，它與平靜的睡前習慣所產生的心理效應關係更為密切。
Another theory is that drinking warm milk could subconsciously remind you of having milk at bedtime during your early childhood years. These soothing feelings may signal to your brain that it’s time to sleep, making it easier to drift off peacefully.
另一種理論認為，喝溫牛奶能讓你下意識地想起自己在幼年時期睡前喝牛奶的記憶。這些舒緩的感覺可能會向你的大腦發出訊號，告訴你該睡覺了，讓你更容易平靜地入睡。
Still, there’s not enough evidence to guarantee any particular result from adding milk to your bedtime routine.
儘管如此，沒有足夠的證據來證明在睡前養成喝牛奶習慣會有什麼特別的效果。
SUMMARY
總結
Milk contains several compounds known to support healthy sleep cycles. Plus, the psychological effects of a bedtime routine that includes milk may improve your ability to fall asleep, but more research is needed.
牛奶中含有幾種已知的有助健康睡眠週期的化合物。此外，睡前喝牛奶這個習慣的心理效應可能會幫你更快入睡，但還需要更多的研究。
來源：Healthline
編輯：董靜
來源：中國日報網
