Categories
Circadian Sleeping Troubles

Take a Break (From Social Jet Lag)

Why do you go to sleep when you do? 

Sure, there’s a big part of it that’s physical: You go to sleep because you’re sleepy. But you might also stay awake, even when you’re on the verge of collapsing from fatigue because you have work to get done. Or because your neighbor is practicing a percussion solo at 2:00 am. Or because there’s something mildly fun happening on the internet.

It’s like you’re caught in a tug of war, with your body on one side and eighteen different kinds of social pressure on the other. When your body finally triumphs and drags you into sleep, it’s winning out over incoming texts from friends, the snare drum next door, and that interesting passage in the book you’re reading. Team Body can get a boost from a stronger circadian signal for sleep, but it can also be helped along by that responsible part of our brains that tells Team Social Pressure to pack it up and go home, since “We have to get up early tomorrow, folks.”

The absence of this internal chiding is why people tend to stay up later on the weekend than on the weekdays, which shifts their circadian clock’s timekeeping, which makes it so they can’t fall asleep early enough on Sunday, which makes them end up feeling like a right proper Garfield on Monday. This is called social jet lag, and it’s been linked to lots of bad things

But what if we had a very, very long weekend? In other words: how do we sleep when we’re on break? 

I’m going to talk about this through the limited lens of a paper I was an author on in 2017, with collaborators at the University of Chicago. We looked at how people’s Twitter activity patterns changed as a function of where they were living and the time of the year. Tweeting isn’t the greatest proxy for sleep and wake, but we can at least conclude that if someone is posting a tweet, they’re probably—though not necessarily—awake.

You can make plots like the below, where the blue lines show the (normalized) amount of tweets at any point in time over the course of the day, on weekdays (dark blue) versus weekends (light blue). 

When the lines are low, less tweets are happening then. When the lines are high, more tweets. In the plot on the left that shows February tweeting, you can see a huge difference between weekday and weekend tweeting. In the plot on the right, for August, the minimum points for tweeting (the troughs) are nearly the same.

I remember seeing this and thinking, “Ah-ha! Seasonality effects! Human behavior is changing because the sun is changing over the year!” This, I thought, would be very interesting to report on. 

Then somebody on the team (one of my brilliant co-authors), wondered if it wasn’t just that people were more likely to be on vacation in August than in February. 

Reader, it was totally that.

Or, at the very least, we found some pretty compelling data to suggest that the reason why “Twitter social jet lag”— the difference between the trough in tweeting on weekends versus the weekdays— was higher in February than in August was not because of the sun being different in those two months, but people’s social responsibilities being different in those two months. 

Just look at the timing of the weekday tweeting trough versus the week of the year (red line), alongside the timing of big K-12 holidays (yellow) in Orange County, FL:

Sure looks to me like every time the kids go on break, people’s tweeting activity shifts later in the day. (You see this in other counties, too).

It’s true that tweeting in 2017 might have been disproportionately done by younger people. But this still means that, according to this proxy for sleep and wake, their social jet lag was decreased. They didn’t have to get up early for school or work, so they didn’t, and there wasn’t much of a difference between their weekdays and weekends. 

Which is a good thing! Don’t get me wrong: society is still set up in a way that punishes night owls more than early birds. But having your sleep be more consistent, and not jaggedly interrupted by the weekend, is healthy. 

This December, as we cruise towards that glorious week between Christmas and New Year’s, the sleep of those of us on vacation time will probably shift later, like we’re in one big, endless weekend. Wednesday will look like Saturday. Sunday night and Monday morning will be no big deal. 

The problem comes when we go back. Because if Twitter activity patterns are to be believed, the coming months are some of the worst in terms of “jet lagging” ourselves on the weekend.

So with the holidays coming up, take the time to rest and sleep in a nice, consistent way. Then keep it going into January. This will mean quashing down the parts of you that push for staying up late on Friday and Saturday as much as you can. But it will also mean that one of the best things about the way we seem to sleep on break will carry forward with you into the new year: better weekday-weekend sleep regularity. 

Oh, and by the way: this sleep regularity? In some ways, it might even be more important to your health than sleep duration. But more on that after the break. 

Categories
Circadian Personal Sleep Meme Review

We Rate Sleep Memes

Here we see Squidward staying up and reading instead of going to sleep. Squidward himself might smugly point out that he’s reading a book, not looking at a light-emitting screen, and use that as an excuse to feel superior. If so, he would be tragically mistaken. There are clearly lights on in the room that he’s using to read while staying up late, and that light will have an effect on his clock much in the same way light from a screen would. After all, most homes are bright enough in the evening to significantly mess up sleep-related processes, like melatonin production. Though Squidward would never accept it, his efforts to prevent circadian disruption pale in comparison to those of his neighbor Patrick, who blocks light by being a starfish who lives under a rock. 

Originality: 3 out of 5. Not being able to put your phone down is a classic meme topic. 

Quality: 4 out of 5. Slight cognitive dissonance caused by the “scrolling through social media” text coupled with the image of him reading a book, but it gave us a chance to talk about how room light exposure matters for circadian rhythms, which is what we’re all here for. 


Let us start by noting that Homer’s perception of his sleep here may be skewed: many people with insomnia overestimate how long it takes them to fall asleep, and underestimate how much sleep they actually get. It may be that a more accurate version of this meme would be “me all night vs me four hours before my alarm goes off”– which is still, to be perfectly clear, a miserable experience. It’s miserable even if you’re objectively getting more than 6.5 hours of sleep per night but perceiving that you’re not sleeping much at all (also known as “paradoxical insomnia”). We love targeting sleep improvements through light exposure over here, but if you’re relating hard to this meme, you’ll probably want to get yourself some cognitive behavioral therapy

Originality: 3/5. This, too, is a pretty typical sleep meme topic.

Quality: ⅘. He looks very cozy at the end there. 


Oh, Leo. Leo, no. This is a terrible idea.

For starters, we know what happens to people who get four hours of sleep a night. First, they have more and more “vigilance lapses” with every passing day (4 hours of sleep a night = circles in the below, black squares = no sleep, white squares = 6 hours, diamonds = 8 hours). 

A vigilance lapse means that something popped up on a screen in front of you for half a second and you didn’t even register it. This is bad if you are, for instance, driving a car. 

People on four hours of sleep a night also fail to get better at subtraction and addition tasks, despite days of practice (see: circles staying flat in the below):

And yes, caffeine can counteract “getting worse and worse at things” to an extent, but so can naps. As the authors of a recent review on fatigue and caffeine write, “It is important for caffeine consumers to understand that caffeine at any dose is not a chemical substitute for adequate healthy sleep.” 

Originality: 4.5/5. Nice shout out to shift workers.  

Quality: 2.5/5. Inscrutable indenting decisions. Objectively bad sleep practice. 

Categories
Circadian Lighting Personal

This Thanksgiving, Get Outdoors

Here’s a fun fact: You probably get way less light exposure during a normal work day than you would if you were out camping.

“Sure,” you say. “That’s no surprise. At home, I have walls around me to block the sun. If I’m camping, I presumably have fewer walls.”

“You don’t understand,” I say, leaning in. “You get way, way less light exposure.”

I’m basing this off a famous circadian experiment from Ken Wright’s group at the University of Colorado Boulder, in which they compared the light people get in modern electrical lighting environments with the natural light they get while camping. 

It’s not a 1x or 2x difference when you go from modern light exposure to camping light exposure. It’s a 13x difference

Thirteen times more light exposure during the day! And this in the winter! It’s nuts. 

Imagine turning your current daily light exposure down by a factor of 13, or to 8% of its current brightness. Two things would probably be true. First, it would be hard to see, so you’d bump into things. Second, and most important from a circadian perspective, it would be hard for your brain to tell the difference between day and night. 

After all, the signal telling your brain that it’s day (light) would be just a tiny fraction of what it was before. It’d be like turning a faucet down to just a thin drizzle. You can tell it’s on if you look for it, but it’s an easy thing to miss. 

In a sense, we’ve already done this with the shift from natural lighting to indoor, artificial lighting. We’ve given up the firehose of light that is sunlight exposure in favor of a much muted signal from our indoor lights and devices. 

If you look at the lighting figure above from Stothard et al., it’s ridiculously easy to see where day starts and stops in the camping conditions (black line). But the picture is muddled for modern electric light (gray line): Day seems to start fairly clearly, but where does it end? There’s this blunted peak in light exposure during the day, and a long, ambiguous tail of light exposure stretching out into the night hours. There’s not really a clear day/night divide. 

This matters for our health. There’s a notion in circadian rhythms science of your circadian “amplitude.” Roughly, you can think of amplitude as a measure of how confident your body’s clock is about the time it thinks it is. Give your circadian clock a clear day/night signal, and this will boost the amplitude. Keep it on a constantly changing, dim-light-round-the-clock kind of schedule and the amplitude goes down. 

In other blog posts, I’ve talked about your phase response curve, which tells you which direction (earlier, later) light will push you when you get exposed to it. But you can also think of the amplitude response curve, which tells you whether your amplitude will go up or down if you get light at a certain time. Generally speaking, the amplitude response curves in our models tell you to go outside right smack in the middle of the day if you want to boost your amplitude as efficiently as possible. 

So this Thanksgiving, get some outdoor light. Sure, yeah, get some exercise while you’re out there if you want. But simply being outside and in the light is a good thing: It’s building stronger, more robust rhythms in your brain. And if you happen to fall asleep hard after eating a big meal– well, part of it might be that your circadian clock’s a little more confident that day is over and it’s time to snooze. 

…part of it. 

Categories
Circadian Lighting Personal Sleeping Troubles

No, we shouldn’t make DST Permanent

I recently got some blackout curtains for my bedroom. This was pretty long overdue: about thirty feet from my bedroom window is a cheerfully bright, energy-efficient street lamp, which—while great when I’m taking the dog out for a nighttime stroll—is the photic equivalent of somebody standing in my azaleas and playing “Seventy-Six Trombones” while I’m trying to sleep. 

I’ve definitely started sleeping longer since I’ve gotten them. But I’ve also noticed that they’ve made it so I need to be even more careful about my other sources of light at night. The reason? They don’t just block my light at night. They also block light in the morning.

I’m thinking about this because it’s almost the end of daylight savings time, and, once again, there’s talk of making it permanent. As a quick guide: Daylight savings time (DST) is the one where the clocks move forward (so it’s lighter at night), while standard time is the one where the clock moves back (darker at night). The “Sunshine Protection Act”, introduced by Florida senator Marco Rubio, encourages states to observe a permanent version of DST, with the argument being that lots of good things could come out of just chilling it with the time change. 

Permanent daylight savings time means not having to change the clocks, and not having to experience that gnarly “lose an hour” in the Spring. It means no confusion about how many hours offset we are from the time in the U.K. and no struggling to remember if you should say EDT or EST when you’re trying to coordinate a Zoom meeting across time zones. As a programmer, I’m generally in favor of anything that makes the totally miserable experience of interacting with dates and times in code even marginally easier. 

But it also means—and I’m talking about permanent daylight savings time here—lots and lots of dark in the mornings. 

This is bad. It’s bad because light at night is fundamentally different from light in the mornings, because our bodies are fundamentally different at night than they are in the mornings.

Note: This picture does not apply if you’re a shift worker, a recent traveler, or otherwise circadianly weird.

Light in the morning does a couple things, but one of the most important ones is that it “advances” our circadian rhythms. It tells our internal clock that night is over and it’s time to get a move on. It makes it easier to fall asleep at night. 

And if you get a lot of light in the morning, it eventually advances you to the point where… it stops advancing you. You enter the part of your daily rhythm where light delays your clock. A sort-of “slow down, what’s the rush” period of your internal rhythm that starts in the mid-afternoon for most people and continues into the early morning.

More light in the morning: The permanent standard time solution.

And that slowdown period is the problem. Because while light in the morning is hitting you in the advance region, which you eventually get advanced out of, light at night is hitting you in the delay region, which is like a temporal sand trap. When you get light exposure in the delay region, your clock gets slowed down, which means you spend more time in the delay region. Which means you don’t feel tired as quickly, which means you get more light, which means you spend even more time in the delay region. It’s a feedback loop that spins out of control. It might be the reason that night owls exist

Permanent DST (gasps in circadian horror)

So if we adopt permanent DST, we’re adopting a schedule where we get more light during the hours most people call night, and much less light in the hours we consider morning. We’re setting ourselves up to fall into the delay region sand trap: More light in the night, making us stay up later and get delayed, and far less light in the AM hours to counteract it. 

This is what tanked permanent DST the first time we tried it. I’m not sure why this doesn’t always get brought up as the very first point against permanent DST, but we’ve totally done it before. In 1973, anywhere from 57-73% of people supported staying on DST during the winter. So they did it, in January of 1974. By the time February and March rolled around, only 19-30% of people still thought it was a good idea, while 43% said it was actively bad. 

What changed? People experienced what happens to your body when you have to kick off your day in the dark of night. They drove to work and caught the bus to school, while the sun waited to rise until 8:00 am. They didn’t like it, and rolled the decision back before the next winter came around. 

You might say, “well, time is a fake idea. Who says you have to start your day before 8:00 am?” This is a fair point. We could, societally, shift the normal times we do things to match whatever schedule we wanted. In China, where the entire country is on the same time zone, places like Kashgar (in the far west) have shifted their normal operating hours to reflect the fact that the sun might not come up until 10 am. 

But it’s a lot tougher to change social standards of when school and work “should” start in every town in the country than it is to pass a bill changing the time that appears on your phone. Which is why we shouldn’t do it: Permanent DST will put us on schedule where our traditional social standards for when things should happen are at odds with our biology, sabotaging our sleep and circadian health.


If we want to stop the whiplash of changing the clocks twice a year, why not do permanent standard time? I’m in favor of this. It reduces confusion the same way permanent DST does, but without the corresponding damage to our internal rhythms. Sure, it might mean that 9:00 pm is dark, even in the summer. But darkness at the right times is a healthy thing. And from a safety perspective, there are lots of street lamps and other sources of light at night these days that are very good at their jobs. 

Which brings it back to me and my blinds: I’ve needed to be more careful about my other sources of light at night lately because my blackout curtains mean I don’t get woken up by the sun. That’s not a big problem: I can wake up in the dark and yank them open myself, like one of the townsfolk in the first song in Beauty and the Beast

But if I get too much light at night from non-streetlamp sources, like watching Succession on my computer or looking at Succession memes on my phone, my ability to wake up in the dark in the morning is going to be less reliable, jeopardizing my exposure to that vital morning light. And I’m lucky that there’s even morning light to get: with permanent DST, I could be hopping on my first calls of the day while the sky is still black outside. 

My point is that social pressures already make it hard for us to get the darkness we need at night (let’s face it, screens are fun) and the light we need in the morning. We shouldn’t make it harder for ourselves with a change to a system that’s already failed once. Permanent daylight savings time is a no-go. Permanent standard time? Call me. 

Categories
Circadian Personal

Let’s talk about Time-Restricted Eating

I have always been a good eater.

Back when I was in college—waking up at 4:50 am for crew practice, staying up until 1:00 am working on problem sets, and sleeping in until noon on my days off—I could eat pretty much any food in any amount at any time of the day. And I mean anything, anytime. Think: bootleg s’mores made out of saltine crackers and ice cream toppings. Cooked in the microwave. At 6:45 in the morning. 

Something changed in graduate school, when I stopped having wildly irregular sleep schedules and got my circadian act together. I just… didn’t feel hungry after a certain point in the evening. And if I tried to eat something very late in the day—say, a midnight snack— it actively made me feel… kinda bleh. 

My philosophy around food has always been to eat when you’re hungry. But once I was on a regular schedule, I stopped feeling the constant, slow-burning hunger I’d had back when I was up at all hours. I still felt hungry, but only at certain times of the day. The rest of the time I wouldn’t really feel hungry at all. You might say that my eating and hunger patterns became more strongly rhythmic.

Enter circadian rhythms. It makes sense to think that our bodies might be more prepared to handle food at some times (like when we’re awake), rather than others (like when we’re supposed to be asleep). And the same way light at night confuses and disrupts the central clock in our brain, so too could food around the clock confuse and disrupt the peripheral oscillators in our organs. Buying all this, how might you avoid this disruption? Eat what you want, but only over a portion of the day. 

This is time-restricted eating, or TRE: the idea of keeping all your eating to the same window of time every day. Usually this window is 8-10 hours long. So if you get up and start eating at 8:00 am, you might restrict your food intake to ten hours a day and stop meals after 6:00 pm. Or you might hold off on eating until 11:00 am, in which case you’d wrap up food for the day around 7 – 9:00 pm. You might only do this for five days of the week, or you might do it every day. Regardless, this isn’t about actively trying to cut calories. It’s not about how much you eat, it’s when. 

TRE came out of the work of Dr. Satchin Panda, a professor at The Salk Institute and author of The Circadian Code.

His group found that simply restricting eating windows led participants in their studies to feel more energetic, sleep better, and show improvements in cholesterol and blood sugar. He’s even got a research app you can download to participate in his group’s studies at myCircadianClock.org (note: we’re not affiliated with this project, we’re just fans). 

Not everyone can manage TRE with their job (night shift workers, for one, often have to fuel whenever they can), and people with underlying health conditions should talk to doctors before giving it a try. But as someone who fell into a time-restricted eating schedule somewhat by accident, I have no plans of quitting anytime soon. I’ve lost a fair amount of weight since my undergraduate days, and it’s not because ever stopped eating s’moretines. I’ve just gotten to the point where my body has a much clearer signal than it used to for when it wants food and when it doesn’t. 

So take a look at Dr. Panda’s website, or book, and consider if TRE makes sense to try out. After all, the timing might be right for you. 

Categories
Circadian Lighting

Time to Win

Lately, I’ve been watching clips from the Olympics, getting misty-eyed when the athletes hug at the end, and then stalking the winners on social media: a normal Saturday night in 2021. I have a shirt that looks like that, I think as I scroll through photos of them lifting approximately three times my body weight. We’re not so different, you and I, I think as they hit a five-inch target from a football field away. 

Categories
Circadian Lighting Personal

The Right Light

I recently went on a trip to California.

Coming from the East Coast, this was a three-hour shift west. To adjust to California time, I needed to delay my circadian clock. One catch, though: my flight out was extremely early in the morning. That meant, like it or not, I was going to advance myself as I set out on the journey.

Let’s back up a little. We talk about directions your internal clock can shift as advances or delays. Think of advancing as hustling your clock along, making your circadian rhythms more like those of people in time zones east of you. Delaying, on the other hand, is like a temporary slowdown for your clock, making your rhythms more like people living to your west. Light at different times of the day advances or delays you, depending on your clock’s state when you’re exposed to it. 

Categories
Shift Work

Living with Shift Work

It’s no secret that working night shifts does a number on your body.

From increased risks of cardiovascular disease, diabetes, and cancer, to excessive alcohol consumption and worsened nutritional intake, shift work is associated with a whole host of nightmarish health effects. 

The simple solution would seem to be to get rid of jobs that put people on work schedules that are brutal to their well-being. But society needs 24-hour emergency and healthcare workers to function, which means night shift work is here to stay.

It’d be great if there was a pill you could take to erase shift work’s negative effects. Unfortunately, there’s not much in the way of pharmacological solutions that work for shift workers at present. There is hope, however: non-pill solutions, like changing shift timings and light therapy, can offer relief to shift workers. In this blog post, we’ll cover what we know about what works for shift workers.

Categories
Technology

Wearable Headaches (and how to fix them)

So you want to get somebody’s internal time from a wearable…

Let’s talk about wearable data. On the one hand, wearables are an incredible innovation, allowing self-quantification and anomaly detection with unprecedented ease, at unprecedented scales. 

On the other hand, they’re a data science nightmare. Or three nightmares, really. 

Nightmare #1: All the devices are different, and you have to use different ways to get raw data off them. 

Sure, apps like Apple Health that act as clearinghouses make this easier for you. But you can’t use Apple Health for everything. Sometimes, wearables require permission to be granted for you to access their full data. Sometimes, wearable companies go out of business after you’ve built an infrastructure to work with them. 

Can you process heart rate signals from two wearables using the same algorithm? What if they decide what counts as a “step” in different ways? What if the firmware changes? People have certainly thought about these questions, and that’s the whole point: you have to think about them. The effort of keeping track of everything adds up. 

Categories
About Arcascope

Welcome to Arcascope

Here’s the thing about the name:

I wanted to capture what I thought was most exciting about our company.

Sure, you can sleep better by taking care of your circadian rhythms, but circadian rhythms are about a lot more than just sleep

And yep, we’re a circadian rhythms company, but we’re one founded by people who are (primarily) mathematical biologists. 

Rather than trying to figure out what time is in a person’s brain with a gold standard test (for instance, by taking repeated saliva samples for hours in the dark), we use math models to infer what’s most likely to be going on in their brain, given all the inputs that have gone into it. 

Rather than trying to estimate their internal time from a single measurement or number, we use lots of data, collected on the timespan of weeks to months. 

In a sense, we’re using our algorithms to see inside a black box: letting us predict what’s going on in your head, without the need for invasive testing. That’s what I think is most cool about our tech.