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Quantifying Your Sleep

A group of experimentalists who track various patterns about themselves investigate slumber.
April 5, 2011

Last week, in a converted garage in Somerville, Massachusetts, a group of about 30 eager experimentalists and curious insomniacs gathered to share the results of their latest investigations. Several members of the group had spent the month of March using a consumer device known as the Zeo to track their sleep patterns and observe how the patterns change with different factors, including weather, color of ambient light, and location. While the individual results aren’t going to change our notions of sleep, the overall trend of self-experimentation just might.

Sweet dream: Devices such as the Zeo, a headband with a built-in sensor worn during sleep (top), are allowing consumers to track a growing number of personal and health parameters. A base station (bottom) wirelessly receives the sleep data and displays it for the user.

The Boston-based group is part of a nationwide movement known as Quantified Self, a collection of people who employ the growing numbers of sensors, trackers, and data analysis tools to monitor intimate details of their lives. While more-traditional scientists may argue about the objective value of an experiment with an N of 1, quantified selfers, as they call themselves, say that is beside the point. They are investigating how various physical variables affect the quality of their lives in the most rigorous way possible.

Physical activity, heart rate, and nutrition are the most commonly tracked personal metrics, but new tools that are gradually moving from medicine into the consumer world have opened additional vistas in personal exploration. Zeo’s sleep monitor, a consumer device that costs $199, uses a single sensor worn on the forehead to track electrical activity; specialized algorithms determine whether the wearer is awake or in deep, light, or REM sleep, as well as how many times she or he wakes and total duration of sleep. (Topics for future meetings include blood glucose monitoring and perhaps even personal genomics.)

While Zeo’s developers originally envisioned the device as an alarm clock to wake users in their lightest phase of sleep, the company quickly realized that people are fascinated by all aspects of slumber; we spend one-third of our lives asleep, and many people are desperate either to get more of it or to function better on less. But it’s a state that has been difficult to self-monitor. “People are really curious about sleep,” says Stephan Fabregas, a research scientist at Zeo who spoke at the meeting. “They want to know if they are normal and, if not, what they should do about it.”

Zeo lent the group a number of devices for a month to see what kind of experiments members would come up with. Jacqueline Thong, a self-described “good sleeper,” found she slept equally well in her bed, on her couch, and on the floor, prompting her to question the value of her expensive mattress. Adriel Irons, who claims to be able to predict the weather, was unable to link his sleep quality to local weather patterns. 

Sanjiv Shah, a former insomniac, had the most dramatic findings. He had already discovered that orange glasses, which filter out blue light, help his sleep. (Research has shown that blue light can affect circadian rhythms.) To quantify those benefits, he used the Zeo, the fitbit (a motion sensor device that tracks daily activities), and a camera trained on his bed to record his sleep for a month: two weeks wearing the glasses for three hours before bed and two weeks without them. The benefits for Shah were clear; without the glasses, he took an average of 28 minutes to fall asleep, but with them he took only four. His deep sleep without the glasses averaged 60 minutes, versus 86 minutes with them.

The caveat, of course, is that it’s impossible to rule out the placebo effect in Shah’s striking results. Matt Bianchi, a neurologist at Massachusetts General Hospital who also spoke at the meeting, says that no large-scale studies have shown that orange glasses have this benefit. But Zeo’s Fabregas says that doesn’t matter. The glasses work for Shah, and in this case, that’s what counts.

Zeo aims to expand the realm of sleep self-experimentation with an API (applications programming interface), as well as an interface that allows users to view their data, and even a data library that gives access to a huge volume of stored sleep data from many of Zeo’s users. Consumers can now integrate Zeo data with that from monitoring programs such as DailyBurn, a calorie tracking program, and RunKeeper, an app that tracks physical activity.

Bianchi, who studies a number of sleep disorders, says an individualized approach to the study of sleep may help shed light on its complexities. He points out that there are huge limitations to how sleep is studied in clinical sleep labs and research labs where people are attached to sensors and entangled in wires. “I have become very skeptical of sleep science and clinical trials, so I have become very interested in what individuals have to say,” says Bianchi, who is developing his own home sleep-tracking tool.

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