The concept of mindfulness involves focusing on your present situation and state of mind. This can mean awareness of your surroundings, emotions and breathing—or, more simply, enjoying each bite of a really good sandwich. Research in recent decades has linked mindfulness practices to a staggering collection of possible health benefits.

Tuning into the world around you may provide a sense of well-being, an array of studies claim. Multiple reports link mindfulness with improved cognitive functioning. One study even suggests it may preserve the tips of our chromosomes, which whither away as we age.

Yet many psychologists, neuroscientists and meditation experts are afraid that hype is outpacing the science. In an article released this week in Perspectives on Psychological Science, 15 prominent psychologists and cognitive scientists caution that despite its popularity and supposed benefits, scientific data on mindfulness is woefully lacking. Many of the studies on mindfulness and meditation, the authors wrote, are poorly designed—compromised by inconsistent definitions of what mindfulness actually is, and often void of a control group to rule out the placebo effect.

The new paper cites a 2015 review published in American Psychologist reporting that only around 9 percent of research into mindfulness-based interventions has been tested in clinical trials that included a control group. The authors also point to multiple large placebo-controlled meta-analyses concluding that mindfulness practices have often produced unimpressive results. A 2014 review of 47 meditation trials, collectively including over 3,500 participants, found essentially no evidence for benefits related to enhancing attention, curtailing substance abuse, aiding sleep or controlling weight.

Lead author of the report Nicholas Van Dam, a clinical psychologist and research fellow in psychological sciences at the University of Melbourne, contends potential benefits of mindfulness are being overshadowed by hyperbole and oversold for financial gain. Mindfulness meditation and training is now a $1.1-billion industry in the U.S. alone. “Our report does not mean that mindfulness meditation is not helpful for some things,” Van Dam says. “But the scientific rigor just isn’t there yet to be making these big claims.” He and his co-authors are also concerned that as of 2015, less than 25 percent of meditation trials included monitoring for potential negative effects of the intervention, a number he would like to see grow as the field moves forward.

Van Dam acknowledges that some good evidence does support mindfulness. The 2014 analysis found meditation and mindfulness may provide modest benefits in anxiety, depression and pain. He also cites a 2013 review published in Clinical Psychology Review for mindfulness-based therapy that found similar results. “The intention and scope of this review is welcome—it is looking to introduce rigor and balance into this emerging new field,” says Willem Kuyken, a professor of psychiatry at the University of Oxford in England, who was not involved in research for the new report. “There are many areas where mindfulness-based programs seem to be acceptable and promising, but larger scale randomized, rigorous trials are needed.”

Two trials published earlier this month in Science Advances also support mindfulness practices. The first found mindfulness-like attention training reduces self-perceived stress, but not levels of the hormone cortisol, a commonly used biological gauge of stress levels. The other trial links mindfulness-like attention training to increases in thickness of the prefrontal cortex, a brain region associated with complex behavior, decision-making and shaping personality. The authors called for further research into what these findings could mean clinically.

Van Dam characterizes the research methods used in both of these studies as sound. Yet he points out both also represent the field’s larger problem—a lack of standardization. Varying mindfulness-like approaches have been investigated over the years, making comparisons of different studies difficult.

Mindfulness is rooted in Buddhist thought and theory. In the West it was popularized in the 1970s by University of Massachusetts professor Jon Kabat-Zinn, a cognitive scientist who founded the university’s Stress Reduction Clinic and the Center for Mindfulness in Medicine. Kabat-Zinn developed what he called “mindfulness-based stress reduction,” an alternative therapy for a variety of often difficult-to-treat conditions. By the early 2000s, the concept of mindfulness had ballooned in popularity. It soon came to have many differing meanings and varying approaches to treatment. “We specifically commented in our article on the fact that many continue to develop novel interventions without fully evaluating those that are already being implemented,” Van Dam says. “I think these studies, while well-designed, may fit within the category of being just different enough from what we already have to prevent us from really knowing whether we could use these results as evidence for [the effectiveness of] other mindfulness-based practices.”

As Van Dam and his co-authors wrote, “[there is] neither one universally accepted technical definition of ‘mindfulness’ nor any broad agreement about detailed aspects of the underlying concept to which it refers.”

“Overall, I suspect that a large number of the health promises will not be fulfilled, mostly because therapies, phone apps and other interventions are being rushed to market without sufficiently rigorous testing and appropriate implementation,” he says. “But given what we’ve seen to date, I suspect evidence may accumulate supporting mindfulness practices for anxiety, depression and stress-related conditions.”

Behavioral and social sciences professor and director of Brown University’s Mindfulness Center Eric Loucks, who was not involved in researching the new paper, agrees there are multiple definitions of mindfulness. But it is the trickiness in bringing a rich spiritual concept into a standardized framework for testing and advising patients that he feels might be tough to tackle.

“One element in defining mindfulness, if considering its roots in Buddhism, is…the Buddha's recommendation that descriptions of concepts like ‘mindfulness’ are like a finger pointing at the moon,” he explains. “It is important not to confuse the finger for the moon. There will always be variations in people's understanding of mindfulness. It is a personal experience.”