活動腕表(actiwatch)是什麼?



現在許多的穿戴式裝置都有監測睡眠功能,門診也會常常遇到爸爸媽媽帶著App的記錄來諮詢。然而這些裝置是否真地都能適用在孩子身上呢?或者說哪些記錄到的數值是可信?哪些是不可信的呢? 這真地需要更多的研究來證實,今天要介紹的是睡眠醫學裡使用最久的穿戴式裝置:
活動腕表(或稱活動計)


外型與原理

活動腕表的外表會隨廠商而有一些小差異,但是大致上看起來就像一隻手錶,功能多一點的廠牌可能就會尺寸大一些、按鈕多一些,但配戴上的舒適感就會下降(註1)。



活動腕表內有活動記錄器和光線監測器,會每隔一段時間(註2)就評估活動的強度和接受的光線強度。所以理論上在夜晚睡覺時,活動量和光線都會下降,等到低於設定的閾值時,分析軟體就會判定這個時間點應該是處於睡眠狀態,而醫師/技術員可以參考睡眠日誌作進一步的修正。


哪些情形需要使用

因為活動腕表可以記錄長時間的活動狀態,所以臨床上常用在以下兩個情況:

1.需要了解日夜周期變化:晚睡晚起?早睡早起?還是作息不固定?
2.在試圖找出”為什麼白天會很想睡”的情況,例如猝睡症/多眠症就是睡眠總時間很長,但睡眠不足症候群就發現夜晚的睡眠總時間長度是減少
 
 
 

圖示說明

淺藍色表示休息時間,也就是躺床時間 (time in bed);稍微深一點的藍色是儀器辨斷為有睡著的時間(total sleep time),但是短暫的清醒片段因為圖片限制,並無法在圖上顯示出來。
而黃色線條代表接受光線的程度;黑色長條是活動量。


作息相對固定,入睡沒太大問題,但夜晚活動量好像有點多…



作息相對固定,但入睡需要花很長的時間哦…



作息不固定…


【和睡眠日誌的差異】

如果家長/病人自己寫的睡眠日誌可信度很高,的確是不需要另外多作這項檢查的;

但有時候孩子躺在床上眼睛閉著,家長可能會以為已經睡著;或是孩子已經清醒在玩,家長因為不同床(房間)、或是家長仍然熟睡中,導致家長不知道孩子已經起床了,那麼就有可以錯估孩子的睡眠時間長度;在這種情況之下活動腕表會評估這個時間點的活動量有沒有低於閾值,相較下會有一個較客觀的評估。

或者青少年半夜起來玩手機,這樣孩子總不好意思寫在睡眠日誌裡吧!這種情況時因為活動腕表有光線監測,能感應到光線變化,就會知道其實是沒有在睡覺。


【和睡眠多項性生理檢查(polysomnography, PSG)的差異】

兩個檢查能診斷的疾病不同哦! 睡眠多項性生理檢查主打對象是呼吸/動作障礙,例如呼吸中止症候群、肢體周期抖動症、不寧腿、快速動眼期動作障礙,而且只能評估一晚;而活動腕表則是針對長時間睡眠/活動狀態,所以比較適合針對失眠、日間嗜睡等病人。


【與市售的智慧手錶或手環記錄睡眠功能有什麼不同】

最大的不同是智慧型手錶或手環的記錄到目前(2024年初)只能分析晚上睡覺狀況,白天活動或小睡記錄與分析功能,廠商並沒有開放給一般消費者使用;而活動腕表是記錄24小時,就可分析一整天的狀況。

但已經有許多研究指出,用同一種分析方法來處理二者的原始資料所得到的一致性是十分高的;也就是說如果廠商與研究者能磨合找到適合消費者的演算法,那或許未來活動腕表的地位會逐漸勢微。

活動腕表可以看到什麼?



不同廠牌的活動腕表會有不同的數字,但大同小異的是以下幾項:
  1. 就寢時間(bedtime)
  2. 起床時間(wake up Time)
  3. 躺在床上的時間(Time in Bed)
  4. 睡眠時間(Total sleep time)
  5. 入睡所需時間(sleep latency)
  6. 睡眠效率(sleep efficiency)
  7. 入睡後清醒時間長度 (wake after sleep onset)和次數(#awake)
軟體會分別計算出每天的數值和配戴腕表這段時間的平均值。
所以您發現了嗎?它沒辦法像睡眠多項性生理檢查(PSG)告訴你為睡不好的原因哦!



使用上需注意事項

  1. 雖然有部分防水功能,但是洗澡或游泳等可能接觸大量水分的情況下請拿下儀器,以免損壞。
  2. 戴在非慣用手;有時候嬰幼兒會戴在腳踝上
  3. 正常活動下請盡量避免衣物遮住活動腕表:因為有光線監測器,如果常常被蓋住,在軟體分析時有時候會被誤判是在睡覺。
  4. 需要簡單記錄活動狀態,至少要包括就寢時間、起床時間和未配戴儀器的時間:這樣可幫助醫師更正確的分析結果。
  5. 最重要的是不要弄丟或損害儀器:目前各家醫院都會要求使用者簽損害賠償切結書。


結論

活動腕表目前仍是睡眠醫學中最可信的穿戴式儀器,但是如同本文所說它賴以分析的基礎僅有活動量和光線,然而目前市售許多類似產品能記錄的訊號更多,包括心律、血氧濃度,或許在作完信效度分析之後,可以期待未來能有更便宜更準確的分析儀器供大家使用。






  1. 在2020年就筆者所知臺灣市場上有三家廠商提供這項產品。
  2. 數據收集的間隔時間至少是1分鐘1次以上。而市售商用穿戴式裝置很難達到這麼快的取樣速度,所以當然反應在售價上。

 --------------------------English (translated by chat GPT)-------------------------------------------


Many wearable devices now have sleep monitoring functions, and clinics often encounter parents who bring in recorded data on apps for consultation. However, can these devices really be applied to children? Or which of the recorded values are reliable? Which are unreliable? This really requires more research to confirm. Today we will introduce the longest-used wearable device in sleep medicine: the actiwatch (activity tracker).

 

Appearance and Principle 

The appearance of the actiwatch may vary slightly depending on the manufacturer, but it generally looks like a watch. Brands with more functions may have a larger size and more buttons, but comfort will be compromised when worn (Note 1).

Inside the activity tracker are an activity recorder and a light sensor, which evaluate the intensity of activity and the strength of received light at regular intervals (Note 2). Therefore, in theory, during sleep at night, both activity and light should decrease. When they fall below the set threshold, the analysis software will determine that this time point is in a sleep state, and the doctor/technician can refer to the sleep diary for further adjustment.

 

When to Use 

Because the activity tracker can record long-term activity status, it is often used clinically in the following two situations:

  1. To understand the day-night cycle changes: late sleep and late waking? Early sleep and early waking? Or an irregular schedule?
  2. In attempting to identify the cause of "feeling very sleepy during the day", such as narcolepsy/hypersomnia, which is characterized by long total sleep time, or sleep deprivation syndrome, which finds that the total sleep time at night is reduced.

 

 

Difference from Sleep Diary 

If the sleep diary written by the parent/patient has a high level of credibility, there is no need for additional testing.

However, sometimes the child is lying in bed with their eyes closed, and the parent may think they are asleep. Or the child may already be awake and playing, but the parent may not know because they are in a different bed (room) or the parent is still asleep, which can lead to an incorrect estimation of the child's sleep duration. In this case, the activity tracker can evaluate whether the activity level at that time point is below the threshold, which provides a more objective evaluation.

Or if a teenager gets up to play on their phone in the middle of the night, they may not want to write it in their sleep diary! In this case, the activity tracker has a light sensor, which can detect changes in light and know that the child is not actually sleeping.

 

Difference from Polysomnography (PSG) 

The two tests diagnose different diseases! Polysomnography mainly targets respiratory/movement disorders, such as sleep apnea syndrome, periodic limb movement disorder, etc.

It is important to note that while actiwatch can provide some information about a person's awake-sleep patterns, they can not provide more information as a full polysomnography test. Therefore, if a person has suspected sleep disorders, they should seek professional medical advice and undergo a full sleep study.


What can you see on an activity tracker?

Different brands of activity trackers may display different numbers, but they generally include the following:  Bedtime ,Wake-up time ,Time spent in bed, Total sleep time
,Sleep latency (time it takes to fall asleep), Sleep efficiency, Wake after sleep onset (duration and frequency of awakenings)
 

The software will calculate the daily values and the average values during the time the tracker is worn. However, it is important to note that the tracker cannot tell you why you are not sleeping well, like a polysomnography (PSG) test can.

Usage notes:

  • Although some models are waterproof, it is recommended to remove the tracker during activities such as bathing or swimming to avoid damage.
  • Wear the tracker on your non-dominant hand; sometimes it can also be worn on a baby's ankle.
  • Try to avoid clothing covering the tracker during normal activity, as the light sensor may be blocked and mistakenly interpreted as sleep.
  • It is important to keep a simple record of your activity, including bedtime, wake-up time, and times when the tracker was not worn, to help doctors analyze the results accurately.
  • Lastly, do not lose or damage the device as most hospitals require users to sign a disclaimer for any potential damage to the device.



In conclusion

Actiwataches are a useful tool for monitoring daily activity levels and sleep patterns in certain situations, such as identifying changes in sleep-wake cycles or investigating excessive daytime sleepiness. However, their accuracy and reliability may vary, and they should not be used as a substitute for professional medical advice and diagnosis.

 

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