Is our sleep getting worse?

It’s a biological fact of life. The birds do it. The bees do it. Even we do it. No, not that.

I’m talking, of course, about sleep, that vital state that lets us recharge and even cleanses the day’s toxins from our brains. But what happens when it doesn’t come easily? And why do some people have an easier time falling and staying asleep than others?

Those are just some of the questions we answer on this week’s episode of Explain It to Me, Vox’s go-to hotline for all the questions you can’t quite answer on your own.

To get to the root of what’s keeping you up at night, we spoke with Jade Wu, a sleep psychologist who specializes in helping people with insomnia. So what constitutes a good sleeper? “It’s more complicated than you would guess, “ Wu says. “We think of getting enough sleep as important for good sleep. But believe it or not, recently some big studies have found that the timing of your sleep can maybe matter even more.”

“If we follow middle-aged people into older age, those who sleep more at more consistent times from day-to-day have lower risk of cancer, heart disease, dementia, and overall mortality,” Wu says. “So it’s about timing, it’s about quality, it’s about quantity, and a host of other factors.” What are those factors? That’s what we tackle this week.

Below is an excerpt of our conversation, edited for length and clarity.

What are the big sleep dysfunctions?

The most common problem I see is insomnia, which is just trouble falling asleep or staying asleep. And that can be from a variety of sources. A lot of times it’s a life stage issue. For example, a lot of women experience sleep disruption during perimenopause and menopause.

And if you go through a job loss or you move or you go to a really fun bachelor party and you don’t sleep for three nights in a row, then you find you can’t get yourself back on track with sleep.

Insomnia is really in the eye of the beholder. There’s not a number cutoff, like say, you take an hour to fall asleep or you have to be awake for two hours during the night to qualify. It’s really if you feel like you’re taking a long time to fall asleep or back to sleep, or you feel like your sleep is very restless or non-restorative. If it’s been happening for more than a few weeks and it’s really interfering with your functioning, then it’s insomnia.

Another big issue is daytime sleepiness. This is kind of the opposite problem, where it’s not that you can’t fall asleep: It’s that you can’t stay awake really well during the day. And this can be from a variety of sources, too.

The most common is probably sleep apnea, which is a sleep disorder characterized by repeated episodes of breathing cessation or shallow breathing during sleep. And this affects everybody. It’s not just older folks. It’s not just people who are overweight or obese. Women actually are under-diagnosed by a significant margin — something like eight or nine out of 10 women with sleep apnea are not diagnosed. That can cause daytime sleepiness, and be a burden to your heart health and brain health. It’s a really important topic that people don’t pay enough attention to.

And then there are kind of more colorful sleep issues, like sleep paralysis, sleep hallucinations, sleepwalking — more of unusual things that happen at night.

We got a call from a listener named Skylar who is curious about sleep chronotypes — the time of day your body naturally winds down and falls asleep. They’re a night owl and they want to know if there’s a trend toward being more accommodating to people who aren’t early birds.

I feel you, Skylar. I am a night owl, too, by nature. And I absolutely agree that society should be more understanding towards us night owls, because there is nothing inherently wrong with it. We all have our own chronotype: It’s like height. It’s kind of a bell-shaped curve. Mostly people are in the middle, and then some people are extreme morning people. Some people are extreme night owls. But society is designed by and for morning people. Those of us who are night owls struggle and we don’t get to sleep at our optimal time; we often don’t get enough sleep.

If you think about it evolutionarily, a tribe of early humans needed a diversity in sleep timing for everyone to stay safe. Let’s say everybody fell asleep at the exact same time, slept through the night, and woke up at the same time.Then that’s easy pickings for a saber-toothed tiger. We night owls should be saying, “You’re welcome” for keeping watch so the rest of you can sleep safely and soundly.

What makes someone like Skylar a night owl? What determines where on that bell curve of sleep people land?

A lot of it is genetic. Melatonin is a time-keeping hormone that our brains release. It usually ramps up in the evening, stays high through the night, and then kind of goes away in the mornings. It signals to the whole body that it’s time to shut down the factories and rest and sleep, or that it’s time to ramp up and get started for the day.

For those of us who are night owls, our melatonin curve starts later and then goes away later, too. So when other people are already soundly asleep, our melatonin curves are still acting as if it’s still daytime. And then in the early mornings, when other people are ready and raring to go, our melatonin is still high in our system, telling us it’s still nighttime. On an individual level, there are things we can do to shift our chronotypes to better kind of fake it as a morning person and to have an easier time waking up.

What advice do you have for people like Skylar, who are night owls living in a world that’s very 9-to-5?

Well, Skylar, if you can swing it, live on the East Coast and work for a company on the West Coast remotely. That’s the ideal situation. I’ve had patients actually do that.

But if you can’t swing that, the best thing is to get lots of bright light first thing in the morning. Ideally, as soon as you wake up, either use a light box or go outside. It’s not enough to just open your shades or curtains. You have to actually be in broad spectrum — full sunlight for about 20 minutes. And that really helps your brain wake up and teach your circadian rhythm to start the day earlier, and to also release that melatonin earlier in the evening too.

The thing about sleep is that it’s universal. Everybody needs it. But so many people have sleep problems. Why do you think it is? What is it that’s so tricky about sleep?

There are so many reasons. I think we probably don’t have enough time to do the whole thing. But I’d love to get on a soapbox sometime and talk about capitalism — and how that has shaped …

I love soapboxes. Yes. Climb on up there, girl.

When the Western world at least industrialized, we took on this, eight hours for work, eight hours for sleep, and eight hours for whatever you will kind of slogan. And so we started taking on expectations and constraints around our sleep that we didn’t have before.

Do we sleep worse than we used to now? I think of all the screentime we have.

I imagine that we probably are a little bit worse at sleep because of everything from the 24/7 access to information we have, to little dopamine hits, to bright lights in the middle of the night, to all of these technology-enabled distractions that can really keep us up when we ought to be sleeping.

Why is getting good sleep so important? What does that do for us?

I consider it equivalent to nutrition in terms of how much it impacts our health and well-being. We really can’t function well without this basic biological drive satisfied. And when it’s not well satisfied, it impacts our physical health, our mental health, our performance, our functioning, our relationships, our sense of creativity, our connections with other people. It just impacts everything.