Sleep tech company Eight Sleep today said that it has raised $50 million in a strategic round led by Tether Investments at a valuation of $1.5 billion. This new round comes after the startup closed a $100 million round last August from investors such as HSG, Valor Equity Partners, Founders Fund, and Y Combinator.

The startup, which sells smart mattress accessories that can track your sleep patterns and adjust temperatures as you sleep, didn’t disclose its valuation for the previous round, but it was valued at $500 million post-money in 2021 when it raised an $86 million Series C led by Valor Equity Partners. The company has raised over $310 million to date, according to Crunchbase.

Eight Sleep said it was free-cash-flow positive in 2025, and plans to use the new funding for new products, global expansions, and clinical validation. The company currently ships its products to over 34 countries.

The company said it wants to expand beyond selling consumer products, and has sought approval from the U.S. Food and Drug Administration for products that can detect and mitigate sleep apnea.

“What we’re building doesn’t exist yet — a system that understands your body better each night and acts on that knowledge. Our goal is to build the defining health technology company of this generation,” Matteo Franceschetti, co-founder and CEO of Eight Sleep, said in a statement.

The company said that it wants to work on a sleep-focused AI agent that controls the temperature, elevation and firmness of its products proactively and prevents sleep disruption. It said that the agent simulates many scenarios before users get into bed and prepares its products for optimal sleep.

Eight Sleep said that its models are trained on proprietary data, and early pilots of its AI-driven guidance have resulted in people changing their habits, such as exercise timing, caffeine intake or sleep schedules, based on the analysis provided by the app.

Last year, the company launched a hydro blanket that controls temperature, and a new pillow cover that can provide temperature control for the head and neck.

Eight Sleep was caught in a controversy last October when users’ mattress accessories stopped working because of an AWS outage as they couldn’t connect to its servers. The beds overheated, and the company had to add an “outage mode” to its products for such situations.

Eight Sleep competes with the likes of BedJet and Chillpad on the mattress and temperature control front, and with Oura and Whoop in the sleep tracking market.