How Much Sleep Do You Need?

One of the most common messages people hear about sleep is that adults need eight hours a night. That idea is not entirely wrong, but it is often treated too rigidly. In general, most adults need somewhere in the range of 7 to 9 hours of sleep. That range matters because sleep need varies from person to person, and it can also change over time.

For people struggling with insomnia, this becomes especially important. Many assume that if they feel tired, the solution must be to spend more time in bed—going to sleep earlier, waking up later, or otherwise creating more opportunity for sleep. While that seems intuitive, it can sometimes make sleep worse rather than better.

In CBT-I, one of the goals is to understand your actual sleep need rather than trying to force sleep to fit an idealized number. Sleep tends to work best when your time in bed matches your body’s actual ability to sleep. When that match is off, insomnia often becomes more persistent.

Sleep Need Is Not the Same for Everyone

The recommendation that adults need 7 to 9 hours of sleep is useful, but it is still a range, not a rule. Some adults function well with a little over seven hours, while others truly need more. The more helpful question is not whether you are reaching a perfect number, but whether you are getting enough sleep to function reasonably well during the day.

That includes things like alertness, concentration, mood, and the ability to stay awake without excessive effort. For many people with insomnia, however, sleep becomes measured almost entirely by the clock. Once a specific number starts to feel like something you must achieve, sleep can become more pressured and less natural.

Sleep is not static across the lifespan. As people age, sleep often becomes lighter, more fragmented, and sometimes earlier in timing. Some adults find that they no longer sleep as long as they did when they were younger. That does not mean sleep is no longer important, or that everyone simply needs less sleep with age. It means that sleep, like other aspects of the body, changes over time.

These changes can also be shaped by factors such as physical health, hormones, medications, activity level, stress, and changes in routine. A sleep pattern that once fit your body well may no longer fit in the same way. This is one reason some people develop insomnia later in life even if they had previously been “good sleepers.” Expectations that were once realistic may no longer match the way their sleep system currently works.

When Trying to Sleep More Backfires

One of the less intuitive parts of insomnia treatment is that trying to sleep more than your body currently needs can contribute to the problem.

If your body is currently able to sleep about seven hours, but you regularly spend nine hours in bed trying to get more, those extra hours do not automatically become sleep. Often they become time spent awake—thinking, worrying, checking the clock, or trying harder. Over time, bed can become associated not just with sleep, but with frustration, effort, and wakefulness.

This is one of the ways insomnia becomes self-sustaining. The problem is not always that there is too little opportunity for sleep. Sometimes the problem is that the sleep opportunity has expanded beyond what your current sleep system can use effectively. The result is more time awake in bed, lower sleep efficiency, and more attention focused on the problem.

Preserving Healthy Sleep Drive

Part of improving sleep is preserving the conditions that allow sleep drive to build naturally.

A consistent wake time is one of the most helpful ways to support this. Waking at roughly the same time each day helps regulate your body clock and gives sleep a more stable rhythm. Limiting naps can also be important, especially if nighttime sleep is already fragile. While naps are not inherently harmful, they can reduce the sleep pressure that would otherwise build across the day.

It is also helpful to be cautious about extending time in bed. When you are tired, it is understandable to want to go to bed early or sleep in after a rough night. But more time in bed does not always create more sleep. In some cases, it creates more wakefulness in bed, which can strengthen insomnia over time.

Daytime light exposure, physical activity, and thoughtful use of caffeine also matter. Alcohol, irregular schedules, and anxiety about sleep can interfere with your ability to sleep efficiently even when sleep need is present. Sleep depends on the interaction of sleep drive, circadian rhythm, and arousal level, and when those systems are out of sync, sleep can become much more difficult.

In CBT-I, we work to find out about your actual sleep need and bring sleep opportunity back into line with your current sleep ability, so that sleep can become more natural, consolidated, and predictable over time.

你需要多少睡眠？

很多人都聽過一句話：成年人每晚應該睡八小時。這個說法並非完全錯誤，但很多時候被理解得過於絕對。一般而言，大部分成年人每晚大約需要 7 至 9 小時睡眠。這個範圍之所以重要，是因為每個人的睡眠需要本來就不同，而且也會隨時間而改變。

對受失眠困擾的人來說，這一點尤其值得留意。很多人會自然地以為，只要自己覺得疲倦，方法就是多留在床上一點，例如早些上床、遲些起床，或者盡量增加睡眠時間。這樣想很合理，但實際上，這種做法有時反而會令失眠持續，甚至加重。

在失眠認知行為治療（CBT-I）中，其中一個重點是了解一個人現時實際的睡眠需要，而不是勉強自己符合某個理想化的睡眠時數。睡眠通常在「臥床時間」與「實際睡眠能力」較為配合時，會來得較自然、較穩定。當兩者不相符，失眠便更容易持續下去。

睡眠需要並非人人一樣

成年人需要 7 至 9 小時睡眠，這是一個有參考價值的建議，但它始終是一個範圍，不是一條硬性規則。有些人睡七個多小時已足夠，日間精神和功能都不錯；也有些人確實需要更多睡眠。與其執着於某一個「標準時數」，不如留意自己目前的睡眠，是否足以支持日間的基本功能。

這包括精神狀態、專注力、情緒，以及白天能否維持清醒而不感到過度吃力。對不少失眠人士來說，睡眠很容易變成一個由時鐘主導的問題。一旦某個睡眠時數變成「一定要做到」的目標，睡眠便會變得更有壓力，也更不自然。

另外，睡眠並不是一成不變的。隨着年齡增長，睡眠往往會變得較淺、較容易中斷，有時睡眠時間也會提早。有些成年人會發現，自己不像年輕時那樣睡得那麼久。這並不代表睡眠不再重要，也不表示每個人年紀大了就一定需要更少睡眠，而是反映睡眠和身體其他功能一樣，會隨時間出現變化。

這些變化亦可能與身體狀況、荷爾蒙、藥物、活動量、壓力水平，以及生活節奏改變有關。過去適合你的睡眠模式，未必仍然適合現在的你。這也是為甚麼有些人即使以往一向睡得不錯，後來仍然會出現失眠。問題未必只是「睡得差了」，有時也與對睡眠的期望未能隨身體變化而調整有關。

當「想睡多一點」開始適得其反

失眠治療中有一個不太直觀、但很重要的觀念：當一個人嘗試睡得比身體目前實際能睡的更多時，反而可能令失眠持續。

例如，如果你的身體目前大約只能睡七小時，但你經常留在床上九小時，希望自己能睡多一點，那多出來的兩小時並不會自動變成睡眠。很多時候，那些時間只會變成躺在床上清醒——想着事情、擔心自己睡不着、反覆看時間，或者愈來愈努力想令自己入睡。

久而久之，床便不再只是與睡眠連結，也可能開始與清醒、挫敗感和壓力連結起來。這正是失眠容易自我維持的其中一個原因。問題未必在於睡眠機會太少，而可能是在於你給自己的睡眠機會，已經超出現階段睡眠系統能有效利用的範圍。結果就是臥床清醒時間增加、睡眠效率下降，對睡眠的焦慮也愈來愈強。

維持健康的睡眠驅力

改善睡眠，其中一個重要方向，是保留有利睡眠自然出現的條件，尤其是讓睡眠驅力（sleep drive）能夠在白天逐步累積。

其中，固定起床時間是最有幫助的做法之一。每天大致在相若時間起床，有助穩定生理時鐘，讓睡眠節奏更規律。對一些人來說，減少午睡也很重要，特別是當晚間睡眠本來已經不穩定時。午睡本身不一定有問題，但如果它削弱了白天累積下來的睡意，晚上便可能更難入睡。

同樣地，當你睡得不好時，很自然會想早些上床，或者第二天賴床補眠。不過，延長臥床時間並不一定會帶來更多睡眠；有時反而只會增加清醒着躺在床上的時間，進一步鞏固失眠。

此外，日間接觸自然光、保持適量活動，以及留意咖啡因攝取，也會影響晚上的睡眠。酒精、作息不規律，以及對睡眠本身的焦慮，亦可能在你明明有睡眠需要時，仍然妨礙你順利入睡或維持睡眠。睡眠並不是單靠「夠累」就會自動發生，它同時受睡眠驅力、生理時鐘和警覺水平影響。當這幾方面互相失衡，睡眠便會變得困難得多。

失眠治療並不是一味鼓勵人「多睡一點」，CBT-I 會以有系統的方法找出你實際的睡眠需要，並把可供睡眠的時間重新調整至與你目前真正的睡眠能力相符，讓睡眠逐漸變得更自然、更集中，也更穩定可預測。