Health tracking is ubiquitous with nearly every “smart” device providing insights into activity and health. Trackers are helpful for accountability on daily habits and they also offer tangible feedback about how exercise, diet, and sleep affect the body’s biometrics. For someone struggling to get quality, restorative sleep, monitoring can be a key to understanding what’s going wrong.

Wearable sleep monitors continue to rapidly evolve. The first generation of sleep trackers used motion to detect sleep. Then, there was photoplethysmography (PPG), which tracked sleep by measuring changes in physiological markers, like blood oxygen saturation, heart rate, and heart rate variability (HRV).

While these methods are fine approximations, they’re not as reliable as the gold standard in sleep tracking: electroencephalography (or, as its more commonly known EEG).

For years, EEG was only available in a lab setting — which wasn’t accessible (or convenient!) for all sleepers.

“EEG is a phenomenally sensitive tool for measuring brain dynamics as you sleep. It's not new; it's been around for 100 years — and for 100 years the form factor has been horrendous,” says Caitlin Shure, Head of Product & Marketing at NextSense. In the lab, this typically means wearing a cap with small metal disks called electrodes on the inside and a tangled mess of wires on the outside. You look like a Wi-Fi router come to life, and a white coat tells you, "Just sleep naturally!" — while you're hooked up to enough tech to power a spaceship.

However, recent technological advancements have put the power of EEG into devices consumers can use in the comfort of their own home — empowering people with the technology they need to actually track and improve their sleep.

But how does EEG work? Why is it so effective? How has it been used to track sleep — and how is it changing the way we track sleep at home?

Let’s take a deep dive into EEG tracking and how the latest devices can help you sleep:

What is EEG?

Electroencephalography is a non-invasive technology for measuring electrical activity in the brain, or the signals brain cells use to communicate. That data can be used to diagnose a variety of neurological issues and brain disorders, including epilepsy, stroke, Alzheimer’s disease, and brain damage. It’s also extremely effective at measuring what’s happening in the brain during sleep, which can help diagnose sleep disorders and give anyone insights into their sleep quality.

Historically, EEGs have been performed in a lab. When you arrive, a technician applies a sticky gel to various spots on your scalp. This gel reduces resistance between the electrodes and your skin, leading to more accurate readings. Then you don a Medusa-like cap fitted on the inside with electrodes that sit atop the gel and on the outside with snaking wires that attach to the recording device.

The electrodes measure brain’s electrical dynamics, which are recorded on a graph as waves, where they can be used as a diagnostic tool. 

From a sleep tracking perspective, analyzing brain wave activity sheds light on how long you spend in various sleep stages, which can help you better understand the quality of your sleep. The most commonly studied brain waves for sleep are:

• Delta waves (0.5 to 4 Hz): The slowest of the brain waves, delta waves are associated with deep sleep.
• Theta waves (4 to 7 Hz): Theta waves are associated with drowsiness as well as very light stages of sleep. (That feeling where you’re not quite asleep but also not quite awake? That’s theta waves.) 
• Alpha waves (8 to 12 Hz): Alpha waves are associated with a relaxed — but awake — state. Generally, alpha waves happen when the eyes are closed and you are physically and mentally relaxed (like during light meditation).
• Sigma waves (12 to 16 Hz): Also known as “sleep spindles”, sigma waves happen during non-REM sleep and play an essential role in memory consolidation.

This data can also be helpful in diagnosing sleep disorders like obstructive sleep apnea (OSA) or narcolepsy.

EEG vs. traditional sleep trackers

Numerous wearables on the market claim to help improve sleep. But most of these devices have two drawbacks.

First, many have their own methods of analyzing and presenting data and assessing sleep quality (for example, by offering a “sleep score”). Since there’s no standardized way of tracking and assessing sleep across devices, it’s hard to scientifically validate results or discern what the data actually means.

Second, the technology used to track the phases of sleep are approximations based on related signals like heart rate, movement, breathing, or body temperature. One study tested multiple popular sleep tracking devices and found that the devices were significantly less accurate at tracking sleep stages when compared to a sleep study using EEG technology. Because of this, according to one 2022 study, these devices “are not well-adapted to monitor sleep disorders.”

EEG sleep tracking outside the lab

EEG is the most accurate way to track sleep, assess sleep quality, and diagnose any sleep issues or disorders. And for some people (like people with significant sleep disorders), the best way to access EEG technology is in a traditional sleep study. But sleep studies aren’t necessary or accessible for everyone — and for years, EEG technology was out of reach for many.

But now you no longer have to choose between inaccurate sleep trackers and signing up for a sleep study. At-home EEG sleep trackers give you access to the gold standard of sleep diagnostic tools — packaged in an accessible piece of tech designed for everyday use. 

For example, Tone Buds smart earbuds use advanced EEG sensor technology to accurately measure real-time brain wave activity. Tone Buds then uses that data to deliver customized audio to help you fall asleep and stay asleep, as well as actionable insights to improve your sleep in the long run.

At-home EEG sleep trackers offer a host of benefits, including:

• Convenience: With home EEG devices, you can accurately track your sleep and measure brain wave activity any time from the comfort of your own home.
• Accurate data: Since a lab is a far cry from your bedroom, the data from your study may not tell the whole story of what’s happening with your sleep. With an at-home EEG sleep tracker, you can capture real-time data over time, in your normal sleep conditions, ensuring that your results are indicative of your sleep as a whole.
• Affordability: Lab sleep studies can be expensive, with most sources reporting an average of $3000—although costs may go as high as $10,000. (Total cost will depend on a variety of factors, including insurance coverage, location, and the type of sleep study). EEG sleep trackers give you access to the same data at a fraction of the cost of a sleep study. For example, Tone Buds have an MSRP of $299 USD.
• Early intervention: Generally, sleep studies are reserved for people with serious sleep problems. But just because you don’t have a diagnosable sleep disorder doesn’t mean that you don’t wish you could get better sleep. With an at-home EEG sleep tracker, you can intervene before things snowball into a bigger issue.
• Actionable insights: Based on your personal sleep data, EEG sleep trackers offer actionable insights to improve your sleep and your overall health. For example, if your data shows that you’re taking a long time to fall asleep (called “sleep onset latency”), you might try cutting out caffeine after noon or getting into bed later to nod off faster and get better rest.

The Tone Take: The future of sleep improvement is here

EEG has long been the gold standard in measuring brain activity, evaluating sleep, and diagnosing sleep disorders. And thanks to the rise of wearable EEG devices like Tone Buds, this technology is transforming the future of sleep health and improvement. For the first time, rather than getting a random sleep score, people can access their brain data on any given night. And it’s more than numbers. Tone Buds delivers personalized, science-backed suggestions for how to optimize sleep-related behavior, making it easier and more convenient to better understand your sleep, improve your sleep, and live more full, energized lives.