Newsletter #252

We are about a week away from the start of Daylight Saving Time in the US. That time change, obviously, means that we "lose" an hour of sleep. Fortunately, this is mostly a transient issue, since our biological clocks eventually recalibrate to the new schedule.

However, many of us are stuck in a chronic state of social jet lag — meaning that our biological clocks are constantly misaligned with the time when we are required to be awake and alert. This leads to a pervasive reduction in overall sleep year-round, which is accompanied by a host of acute performance decrements and potentially long-term health issues.

One group in whom this has been studied extensively is students. Students are an apt model because they generally have strict schedules forcing them to wake up earlier and because adolescents tend to have a delayed circadian phase that drives them to fall asleep later. This is obviously a recipe for inadequate slumber, and it likely has grim implications for their grades, as you'll see in the two new studies described below.

But what can be done about it?

Well, one intervention that might help is introducing some light exercise. One experiment found that people who went for a 15-minute jog experienced a performance boost in cognitive tests that measured mental speed and attentional control, compared to a control group that just stayed inside and relaxed. Furthermore, moderate-intensity exercise has been shown specifically to reverse cognitive deficits associated with sleep deprivation. Finally, it is known that exercise enhances sleep quality, meaning that even if you're not getting a ton of sleep, the sleep that you do get is more likely to be restorative.

There are some other lifestyle modifications, as well as technological innovations, which might be useful here, and which we hope to share through our coaching program coming up here shortly.  👀 We have spent years researching and developing content related to sleep in general, but especially the role of sleep in cognition and daily performance, so we think we have a lot to offer in this area. If you’d like to be the first to know when we kick that off, please head to this link and take 30 sec to fill out the short form.

To examine how early morning classes influence sleep and academic engagement, researchers in Singapore analyzed data on sleep and attendance from thousands of college students. In order to acquire this kind of information from such a massive sample without requiring active participation, the researchers cleverly analyzed digital activity from these students. To capture lecture attendance, they looked at Wi-Fi connection logs. Basically, if a given student's laptop or other digital device was connected to the Wi-Fi for the building or lecture hall where the class was being held, that would be a pretty reliable indicator that they were indeed attending that class. Then, to measure sleep patterns in the students, they analyzed time-stamped logins on the university’s Learning Management System, the online platform through which students download course materials, submit assignments, and do other class activities. Prior research has validated this kind of activity as a way to estimate sleep-wake patterns in students. Unsurprisingly, the analysis of the Wi-Fi connection logs revealed that lecture attendance was ~10 percentage points lower for classes at 8:00 am, compared to later start times. When they looked at a subset of students who were wearing sleep trackers, the situation looked even grimmer — students did not wake up in time for nearly one-third of classes that took place at 8:00 am. And despite frequently oversleeping, the researchers found that nighttime sleep was about an hour shorter for early classes. This observation mirrors a number of prior studies examining how different school schedules influence sleep patterns. For example, when Brazilian researchers compared middle school students who attended either a morning or afternoon school shift, they found that the morning students got one hour and forty-five minutes less sleep nightly, compared to their afternoon counterparts. Finally, the researchers analyzed the grades of more than 33,000 students and determined that being enrolled in more morning classes was associated with a lower GPA. It seems likely that reductions in sleep were responsible for the poorer academic performance - and the next study lends further support to that notion.

To examine how objectively measured sleep duration affects grades, a team of researchers recruited more than 600 first-year college students enrolled in three independent universities in the US, and equipped them with Fitbits. The students wore the trackers for one month, early in the academic term, to capture data on sleep duration and timing. Then, the researchers looked at these students' grades at the end of the term to see how their sleep patterns affected their academic performance. So first of all, the average sleep patterns of these students were honestly pretty bad. Like you might expect. Participants averaged around 6.5 hours of sleep each night, usually catching up a bit on the weekends. Their average time to fall asleep was after 2 am, and their average wake-up time was shortly after 9 am. After controlling for previous term GPA, daytime sleep, and overall academic load, the researchers determined that lower average nightly sleep duration was indeed linked to lower GPA at the end of the term. Again, none of this is super surprising, but I think the most useful takeaway from this study is kind of embedded in the methods. You might have noticed that all of the sleep data was collected early in the academic term. The researchers did this, purportedly, because they didn't think that sleep patterns close to final exams would provide useful insight. Here's why: A prior study in which researchers had students in an MIT engineering class wear Fitbits for an entire semester found a virtually straight-line relationship between the amount of sleep that a student got on a regular basis and their academic performance. But sleep right before major exams did not seem to be critical. As one of the authors of that paper said, “We've heard the phrase ‘Get a good night’s sleep, you've got a big day tomorrow.’ It turns out this does not correlate at all with test performance. Instead, it’s the sleep you get during the days when learning is happening that matters most.” And this totally makes sense. First of all, human experiments have shown that poor sleep makes it much harder to focus and shut out distractions, which makes it less likely that you'll even be able to pay attention to what you're trying to learn in the first place. But we also know that sleep plays a critical role in stabilizing our memories. While we are awake, we are being bombarded with new information - more than we can possibly store. Then when you sleep, your brain goes through and replays this stimuli, and retains the important stuff. It is only when this information is consolidated that you are able to recall it later. So, I think the key takeaway is that chronically getting less sleep than you need, and then trying to cram in more on the weekends or right before important events isn’t going to pay off. Like most aspects of lifestyle, you will see the most benefit if you maintain a healthy sleep pattern most of the time.

Engaging in lifelong learning that promotes plastic re-organization in the brain is an essential piece in maintaining brain health. And the evidence clearly shows that we retain this ability to change our brains throughout our lives. But we often think of learning in terms of acquiring new knowledge and motor skills.

In the latest issue of The Brainjo Connection, Josh discusses why acquiring new perceptual abilities should be part of a complete program of brain fitness.

In the late 1990s, fearing that they might be incentivizing people to attempt dangerous sleep restriction, Guinness World Records decided to stop monitoring the record altogether.

(It is also sort of tricky to verify that someone actually stayed awake for these time frames, due to the occurrence of sudden and extremely brief bouts of slumber known as microsleeps)

That having been said, it is thought that Robert McDonald of Mariposa, California holds that record. In 1986, he embarked on a rocking chair marathon in the front window of a restaurant, which resulted in him spending a mind-boggling 453 hours and 40 minutes awake. That is almost nineteen days!

Needless to say, do not try this at home.

This week, we’d like to highlight our How-to Guide for Smart Daily Light. We evolved in the presence of natural daily cycles of light and darkness. But obviously, the invention of artificial lighting means that we can now fully control when and how much light we’re exposed to, which has altered this relationship. Today, most of us spend the majority of the day indoors, under comparatively dim artificial lights. Then, after sundown, we are exposed to more bright light, and importantly more blue light due to our digital devices. Consequently, we are getting less bright light during the day and less darkness at night.

This is important because light sends crucial signals to the body, and the intensity and timing of this light matters for your health as well as your performance. But fortunately, there is a lot you can do about it. In this guide, we discuss how you can achieve a pattern of natural light and darkness in the modern world by adjusting behavior, modifying your indoor spaces, configuring your devices, and more.

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