Since late last year it has been something of an open secret in some digital health circles that Newton, Massachusetts-based sleep monitoring and coaching company Zeo was winding down its operations and searching for a buyer. At least one investor was making veiled references to the company running out of money during various question-and-answer periods at the mHealth Summit in Washington DC last year. Zeo's absence from the Consumer Electronics Show (CES) in Las Vegas this year -- a must-attend for any company selling devices and companion services to consumers -- was telling.

This past week the Better Business Bureau listed the company as being "out of business" and Zeo CEO Dave Dickinson participated in an online TEDMED event as the company's "former CEO". While there is no official announcement, no known buyer yet, it's clear that Zeo as we knew it is now over.

Zeo's original offering was a sleep monitor that included a wireless-enabled, sensor-equipped headband that users wore at night and a bedside display alarm clock that captured the data transmitted from the headband. When Zeo was first conceived by a group of Brown University students almost 10 years ago, the idea was for an alarm clock that could wake you up at just the right moment in your sleep cycle, during the right sleep stage, so that you would awake feeling refreshed. Zeo's alarm clock had this functionality built right in when it launched in 2009. Before that launch, however, the startup discovered in early product tests that users wanted a device that could do more than just wake them up better, they wanted to know how well they were sleeping, too.

"They wanted to know more about how they could get more REM and deep sleep," Zeo Co-Founder and former CTO Ben Rubin told MobiHealthNews in 2010. "They wanted explanations for why they woke up seven times last night and how they can improve that. So we set about creating not just a smart alarm clock, but a personal sleep coach that would show you what was affecting your sleep and suggest improvements that could be made.”

Zeo's bedside display and subsequent reports showed users when they were in a certain sleep phase and then they awoke during the night. The company also created a composite score to help users to better understand how well they slept one night vs another -- the score was called their ZQ.

Over the years Zeo added new suggestions to its sleep monitoring website, added mobile apps, transitioned into a sleep "coach" instead of a sleep monitor, and even offered a version that bypassed the bedside display alarm clock and transmitted right from the headband to the user's smartphone via Bluetooth.

At last year's Quantified Self conference in San Francisco, it was clear that Zeo was favored over most other tracking devices at the event. Zeo has had to deal with increasing competition from simpler activity tracking devices that suggested users wear them at night to get a basic idea of how well they slept based on how much they tossed and turned throughout the night. Activity tracker companies like Fitbit and Lark are among those that offer that kind of a sleep tracking component, which may have been "good enough" to compete with Zeo's far more sophisticated and -- likely -- more accurate sleep tracking capabilities.

Zeo was also a fixture in Dr. Eric Topol's keynote presentations -- in fact, Topol included a couple of slides about how he uses Zeo to track his own sleep at HIMSS13 last week.

Former talk show host Regis Philbin also famously tested out Zeo soon after it became commercially available, and after discovering how much trouble he was having sleeping at night, the data he gathered with his Zeo encouraged him to go visit his doctor. Turned out he had sleep apnea.

Zeo was always a consumer product and not meant for people who had sleep disorders. The company made early inroads with retail channels like Best Buy, back when Best Buy wasn't selling anything related to health and wellness. Zeo made an effort to make clear that its device was not a medical device, but it also worked with medical researchers who were looking for a less expensive way to include sleep monitoring data in their research.

While the debate over why Zeo didn't make it is one that will likely continue for some time, one thing that clearly set it apart from the rest of the companies working in digital health today is that Zeo not only had to manage the usual issues that all startups have to deal with as they launch and grow, it also had to convince the world that sleep health was important. For those that have looked into the issue, there's no question that there is a sleep problem underlying many health issues in this country.

Zeo had a disruptive offering. The company did help kick off a discussion about sleep health. Hopefully, its sleep coaching platform finds a home soon.