CVS Health wants to help millions of American workers improve their sleep. So for the first time, the big pharmacy benefits manager is offering a purely digital therapy as a possible employee benefit.

The company is encouraging employers to cover the costs for their workers to use Sleepio, an insomnia app featuring a cartoon therapist that delivers behavior modification lessons.

CVS Health’s push could help mainstream the nascent business of digital therapeutics, which markets apps to help treat conditions like schizophrenia and multiple sclerosis. The company recently introduced, along with Sleepio, a way for employers to cover downloads as easily as they do prescription drugs. The company said it had already evaluated about a dozen apps.

Some industry executives and researchers say the digital services should make therapy more accessible and affordable than in-person sessions with mental health professionals.

Big Health, the start-up behind Sleepio, is one of more than a dozen companies that are digitizing well-established health treatments like cognitive behavioral therapy, or devising new therapies — like video-game-based treatments for children with attention deficit hyperactivity disorder — that can be delivered online. Since last year, a few pharmaceutical companies, including Novartis, announced partnerships with start-ups to develop digital treatments for mental health and other conditions.

So far, the use of treatment apps has been limited. But with the backing of CVS Health, which administers prescription drug plans for nearly one-third of Americans, those therapies could quickly reach tens of millions of people. A few employers have started offering Sleepio, and more are expected to sign on this fall, CVS Health said. Like in-person therapy, the insomnia app does not require a prescription.

“We are at this pivotal moment,” said Lee Ritterband, a psychiatry professor at the University of Virginia School of Medicine who has developed online health interventions for more than a decade. “For years, these have been bubbling under the surface.”

Other experts argue that online therapies may not be ready for mass adoption. In a recent study in Nature, researchers warned that most digital treatments lacked evidence of health benefits. Although first-of-their-kind medical apps that claim to treat diseases must obtain clearance from the Food and Drug Administration, health apps that make vaguer wellness claims — like better sleep — generally do not need to demonstrate effectiveness to federal regulators.

CVS Health said it was carefully reviewing the scientific literature on digital therapies to decide which ones to offer employers. The company selected Sleepio first partly because the app was backed by rigorous, published studies, said Dr. Troyen A. Brennan, CVS Health’s chief medical officer.

“It’s important for us as a pharmacy benefit management company, as a big retail pharmacy, to endorse digital therapeutics when they work as good as or better than medications one can take by mouth,” Dr. Brennan said. “We can give the stamp of approval from having looked at the scientific information.”

Volunteers in randomized studies who used Sleepio reported feeling milder insomnia than people who used a placebo treatment app or online sleep education. But the app has not been rigorously studied against sleeping pills or in-person behavioral therapy.

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CVS Health is offering Sleepio just as health experts have soured on prescription sleeping pills.

In 2018, retail pharmacies in the United States dispensed more than 29 million prescriptions for drugs like Lunesta and Ambien. But the F.D.A. warned Americans in April that taking certain sleeping medications had caused dangerous sleepwalking and “sleep driving,” resulting in serious injuries and even deaths. The American College of Physicians now recommends cognitive behavioral therapy — a proven psychological intervention that can help people change negative thinking patterns — as the initial treatment for adults with chronic insomnia.

Peter Hames, the chief executive of Big Health, said he had hit upon the idea for Sleepio after he developed insomnia. He taught himself to modify his poor sleep habits, he said, by reading self-help books on cognitive behavioral therapy by Colin A. Espie, a sleep medicine professor at Oxford University. He and Professor Espie later founded Big Health to digitize the techniques.

“We are taking evidence-based, nondrug therapies like cognitive behavioral therapy that are traditionally delivered face to face by human therapists and then fully automating them,” Mr. Hames said.

Sleepio unfolds more like a low-key, single-player video game, where the user is on a quest for better sleep, than a clinical health program. The app features an animated sleep expert with a Scottish accent, called “the Prof.” An affable but firm therapist, the bot offers people who have insomnia symptoms a series of six weekly online sessions.

“At times, you may feel like quitting or even give up, but don’t despair. This is totally normal,” the animated therapist says in the first session. “What I can tell you for sure is, if we work closely together on this, we have an excellent chance of defeating your poor sleep.”

Big Health has raised $15 million from investors including Kaiser Permanente, the California-based health system. In 2015, the start-up began selling Sleepio directly to employers, sending them aggregated data on their employees’ progress. Companies pay a fee for each employee who uses the insomnia app, but Big Health declined to disclose its pricing.

Delta Air Lines and Boston Medical Center, two of the companies that work directly with Big Health, said employees who used Sleepio reported improved sleep.

“It feels a lot more like play than work,” said Lisa Kelly-Croswell, the chief human resources officer at Boston Medical Center, which has offered Sleepio since 2016. About 3,000 employees there completed the app’s initial screening questionnaire, she said, while 350 people finished the six-week program.

In several randomized studies that assigned some volunteers to use Sleepio and others to a different treatment, like online sleep education, the Sleepio user group generally had a greater reduction in the time it took to fall asleep and the time spent awake at night. At the end of the studies, however, there was little difference in total sleep time between Sleepio users and nonusers.