Although it’s only been about a month and a half, I feel comfortable saying that coming to the University of Washington to study neuroscience was one of the best decisions I’ve made in my short, mostly indecisive life. I’ve been lucky to interface with some of the world’s leading neuroscientists on a daily basis and learn from them about topics like vision, decision-making, sleep, drug addiction, brain tumors, virtual reality, memory, robotics and artificial intelligence.
After a whirlwind first couple of weeks spent completing last-minute fellowship applications, heading into the Cascade mountains for science retreats and exploring Seattle, I’ve finally started to get settled in. The first year of the program requires “rotating” through three different labs, where I’ll need to complete a series of mini-projects. Come June 2016, I’ll have to decide on a thesis lab, where I’ll spend the next few years trying to answer a new question about how the brain works.
My first rotation is with circadian neurobiologist Horacio de la Iglesia, where we’re studying sleep architecture and circadian rhythm in Dravet syndrome. The disease, which is caused by a single genetic mutation, causes severe childhood epilepsy, symptoms of autism spectrum disorders (ASD), learning impairment and sleep disruption. The goal of the project is to better characterize how sleep is affected by this mutation at a neurobiological level in the hope that sleep-based therapies can be developed for patients with epilepsy, autism and learning disorders.
Although my focus is on the Dravet syndrome project, the de la Iglesia lab has recently been in the news for a very different set of discoveries. In August, Horacio and his colleagues published a study demonstrating that access to artificial light in a traditionally hunter-gatherer society is linked to shorter sleep duration. The team studied two separate communities of the Toba tribe residing about 30 miles apart in the Argentinian Chaco. One had access to electricity and artificial light while the other didn’t, but they were otherwise ethnically and socioeconomically very similar.
By fitting participants with actimeters (basically, fancy wrist watches that can detect movement and other physiological or environmental indicators that the wearer is asleep) and asking them to fill out daily journals, the researchers were able to gather information about sleep stage, duration, onset and wake time. Participants in the tribe with access to artificial light got about an hour of sleep less on average than the tribe without, while both tribes tended to sleep longer in the winter than the summer. While there are plenty of laboratory studies out there suggesting that artificial light disrupts sleep, this study was one of the first to investigate these effects in a natural setting.
Still, others think that these concerns are probably completely overblown. Just two months after Horacio’s study was published, another group study out of UCLA reported that three different hunter-gatherer tribes without access to artificial light at similar latitudes in Tanzania, Namibia and Bolivia don’t sleep any more than modern humans in industrialized societies. As in the Toba study, the team used actimeters to gather information about sleep duration, ambient light and temperature. The findings were widely reported by a number of different news outlets.
While these results may be captivating, particularly to the typical screen-addicted modern human, the authors get a little overzealous when they make the claim that:
“the observed patterns are not unique to their particular environmental or cultural conditions but rather are central to the physiology of humans living in the tropical latitudes of the San and Hadza groups, where our species evolved…sleep in industrial societies has not been reduced below a level that was normal for most of our species’ evolutionary history”.
There are a number of big problems with this suggestion. First, it assumes that the fundamental physiology underlying sleep hasn’t changed much, if at all, in the approximately 2 million years since humans began migrating out of Africa. While that may be a blink of an eye on an evolutionary time scale, there’s no reason to think that the staggering array of social and environmental conditions humans across the planet have faced in the last 2 million years wouldn’t place extraordinary selective pressure on certain characteristics of sleep. Second, the study relied solely on actimeters to determine sleep and wake times, which present a number of technical problems and sources of error that can be ameliorated by coupling them with a sleep diary like the one in the Toba study. Third and most important (though definitely not last – there are number of problems with their statistical analyses I won’t go into here), the study didn’t include any control groups with access to electricity and artificial light to compare the three tribes against. Without this crucial control, it’s hard to make any definitive conclusions about how modernization has or hasn’t changed our sleeping patterns.**
While this debate may remain open-ended, it’s probably safe to say that shutting off your computer, smartphone, tablet, television or any other screen you may feel a compulsion to incessantly check before bed wouldn’t hurt. Of course, there are a number of compromises out there for screen junkies like myself, such as f.lux. But if there’s any bit of simple practical advice I can offer after spending the last couple of months studying circadian rhythms, I’d say that assaulting your retinas with social media feeds full of asinine bullshit like this probably won’t help you fall and stay asleep.
** Little disclaimer: I should note that these are my own views, and don’t necessarily reflect those of Horacio de la Iglesia or anyone else on his team.
Evolutionary psychologist, author and podcaster Christopher Ryan talking about hunter-gatherer societies (though not about sleep). I recommend checking out more of his stuff if you’re at all interested in the kind of research described above: