LEESOL, a Busan-based mental healthcare startup, has closed a $2.07 million (KRW 3 billion) Series A2 bridge round, pushing its total funding past $5.24 million (KRW 7.6 billion). The company builds wearable devices and apps that use brainwave entrainment to treat sleep disorders, depression, and other neurological conditions.

BNK Venture Investment led the round, joined by SPACETIME Investment, Soo Investment Capital, and returning backer ViNe Ventures. The raise comes roughly a year after LEESOL’s $2.76 million (KRW 4 billion) Series A in 2024.

Each investor brings more than just capital. BNK Venture Investment — whose backing was partly driven by LEESOL’s designation as a Busan “Baby Unicorn” — is expected to help the company tap into the city’s local infrastructure and distribution channels. The SPACETIME partnership opens a door to iScream Media, a leading digital education platform for elementary school students, where LEESOL sees potential for its cognitive health technology. Soo Investment Capital, meanwhile, is expected to facilitate ties with global regenerative medicine companies.

At the heart of LEESOL’s technology is a combination of microcurrent-based brainwave entrainment and AI-powered biosignal analysis. The approach lets the company target a surprisingly broad range of conditions — from everyday stress and poor sleep to depression, chronic pain, and even dementia prevention — without pharmaceuticals.

Its flagship product line, the Sleepisol wearable series, goes a step further than most consumer sleep devices by targeting deep-brain neural activity to stimulate neurotransmitter release. Clinical results from trials at Seoul National University Bundang Hospital have been published in SCI-indexed journals, lending scientific credibility to what might otherwise sound like a bold claim. The devices have now sold more than 50,000 units across Korea, the United States, and Japan.

Commercially, LEESOL is gaining traction. The company posted roughly $1.79 million (KRW 2.6 billion) in revenue in 2025 under the Sleepisol brand and is gunning for over $4.14 million (KRW 6 billion) in 2026. Japan was cracked open through a partnership with the Funai Research Institute, and a formal U.S. market push is slated to begin in 2027.

The companion app, Sleepisol Bio, has crossed 1.7 million cumulative downloads worldwide and earned “2025 Google Play Global Best App” recognition in the Watch category across ten countries, including the U.S., India, Indonesia, and Australia. To monetize that user base, LEESOL plans to introduce a subscription tier in 2026 built around personalized sleep and cognitive health reports.

The company has had a busy awards season as well, picking up a CES 2025 Innovation Award for the Sleepisol Lite, a NextRise 2025 Innovation Award, and a Prime Minister’s Citation at Korea’s 2025 Venture Startup Promotion Merit Awards — all on top of its Baby Unicorn designation from the Ministry of SMEs and Startups.

Fresh funding will go toward improving its core digital therapeutics platform, developing new wellness devices, expanding globally, and securing international regulatory certifications. LEESOL is also preparing to launch DAYZER, an upcoming wearable aimed at sharpening focus and improving performance across learning, work, and athletic contexts — a product the company expects to meaningfully lift revenue this year.

“This round is the market validating, once again, the technology and commercial progress we’ve made,” said Goo-seong Kwon, co-CEO of LEESOL. “Our goal is to grow into a global electroceutical health platform that addresses not just sleep, but depression and cognitive health as well.”