My Watch Says I Slept Badly

Quantifying and monitoring are words that modern personal life almost can't avoid.

From childhood on, we're always quantifying and monitoring something: our bodies, our weight, our grades, our 1 km run time, our one-minute jump rope count.

Behind all this quantifying is a standard: how much you have to hit before you get the verdict of a qualitative jump. Say you're a middle school student. Your 1 km run has to hit 4:05 (it varies a bit by region) to get full marks. If you run 4:06, sorry, a one-second gap makes a qualitative difference.

So quantified monitoring is something we've never been able to do without since we were young, and almost everyone, living in this environment, instinctively uses numbers to monitor lots of things.

As adults, for example, we judge a job by how much it pays and wealth by how much is in the bank. In daily life, we judge ability by how much we can drink, and prove sleep quality with hours slept.

I'm sure many people use a watch to monitor their sleep. Thanks to leaps in sensor technology, even the cheapest fitness band now gives you the feeling that you've completely mastered your sleep.

I'm someone who wears a watch to bed every night. I used to think I wasn't really a numbers person. But since I switched to an Apple Watch two months ago and started using it to monitor my sleep, I realized it wasn't that I didn't care about numbers. It was that my numbers had always been good, so I didn't have to care.

When I tracked sleep with my Huawei watch, I averaged 8 to 9 hours a night, sometimes 10, and my score was almost always between 95 and 100.

Those numbers influenced me without my noticing, and I thought I slept well.

After I switched to the Apple Watch, my sleep time started dropping, and my daily average went straight down to between seven and a half and eight hours.

After looking at the data, I found that the Apple Watch's sleep figure is the result after subtracting something called awake time. My old watch also tracked awake time, but that number was usually small, say ten minutes at most a night. The Apple Watch shows awake time of half an hour to an hour almost every night.

But I never actually felt myself wake up. The Apple Watch data explains that people repeatedly go through brief awakenings at night that they don't remember, called micro-arousals.

The drop in the numbers made me start to wonder: do I really sleep badly?

But a little thought cleared it up: maybe there is one kind of bad, and it's my watch telling me I slept badly.

I thought carefully about how my sleep feels. When I sleep well, I wake up every morning with a just-came-alive feeling, and stretching in bed in that state is a real pleasure.

That feeling didn't go away after I switched to the Apple Watch. Most of the time it's still there.

And after I get up, wash and eat breakfast, I feel sharp and full of energy, ready to take on anything.

So although the numbers changed, how I feel tells me my sleep hasn't actually changed at all.

At first I cared about the numbers a bit. Later I gradually stopped worrying, because I believe that for sleep, how your body feels should come first.

All quantified data can only be a reference. Only you know whether you really slept well.

For example, sometimes I sleep for a long time but only lightly. That light feeling is obvious after waking: the just-came-alive feeling disappears, my eyes are uncomfortable and I want to rub them, and I keep remembering that I woke up during the night for some reason.

These are the clear signs my body gives when I haven't slept well, and in those cases the watch's score is usually still high.

Many people who want to improve their sleep buy a watch to monitor it.

That's a good thing. We can watch the trend of our sleep through the numbers. But we shouldn't stare at the quantified data and nothing else.

Sleep is a conversation between you and yourself, not between your body and a sensor.

The first one to know whether you slept well is always you.

So next time the numbers make you anxious, try asking yourself first: did I really sleep badly?

We're used to quantifying everything around us, and we forget that talking with our own bodies is hard to quantify.

Today a single watch can monitor heart rate, blood pressure, stress, blood oxygen, mood and more. By talking to the watch and looking at these numbers, we think we know ourselves inside out, and forget only one thing: to have one honest conversation with our own bodies.

Did you really sleep badly?