Sleep tracking tech company Eight (formerly known as Luna) has raised $14 million is Series B funding, according to a statement from the company. The round was led by Khosla Ventures, with participation from Y Combinator and Yunqi Partners.

This latest round will be used to expand distribution of the company’s products, according to the company, and bring’s Eight’s total funding to $27 million. The company’s last $6 million round was announced in early 2006, and in 2015 launched a crowdfunding campaign that tripled its $400,000 goal.

“In 2014 we founded this company with a mission to use technology to improve sleep,” CEO and cofounder Matteo Franceschetti wrote in a blog post on Eight’s website. “With this new funding, our growing team and investors reaffirm the commitment we made in 2014 to bringing the biggest technological evolution that sleep has seen in the last 300 years.”

Eight’s leading products are a line of sleep-tracking mattresses that range in price from $649 to $1,249. Paired with a smartphone app, the mattresses monitor various sleep factors such as heart rate or respiratory rate to discern patterns in the users’ sleeping habits. The mattresses include additional tech-powered features — such as temperature control, smart alarms, and integration with other consumer smart home products like Amazon Alexa — or can be purchased at a reduced price with none of these features. Eight also offers a standalone sleep tracker for $399 that can be placed over a standard mattress to collect these same metrics.

According to a statement, Eight has sold products to more than 20,000 consumers, tracked more than 2.5 million nights of sleep over the past two years, and expects to monitor an addition 12 million by the end of this year.

“The partnership with Khosla is a clear fit for us. They share our vision of a future in which technology and data make healthcare more scientific and consistent,” Franceschetti wrote. “As we continue to redesign the traditional concept of a mattress, we are uncovering the possibilities that tracking biometric signals holds in furthering human healthcare.”

Outside of sleep-tracking wearables, Eight’s most direct competitor is likely Beddit, which makes a sleep monitoring device placed underneath the user’s bedsheets that also connects with an app. A crowdfunding success story, the company was acquired last year by Apple. Another competitor, ResMed and Dr. Oz-backed SleepScore Labs, also offers a monitor that tracks and grades users’ sleep quality from the bedside.