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Most adults in the U.S. get less sleep than recommended across the board, and some racial and ethnic groups fare even worse, according to a new study that used readings from thousands of people who wore commercially available fitness trackers that monitored their sleep.

That's worrisome because research has increasingly shown that inadequate or poor sleep does more than just cause next-day fatigue. It can elevate the risk of cardiovascular disease, dementia, diabetes, high blood pressure, obesity, depression and other health conditions.

The new research, at the ·¬ÇÑÊÓƵ's Scientific Sessions in Chicago, used information from 13,204 people who agreed to supply data from their fitness tracker to the National Institutes of Health's All of Us research program. The findings are considered preliminary until full results are published in a peer-reviewed journal.

The average study participant was 49 years old and slept about 6.4 hours a night. Overall, only about a third of participants averaged the 7 to 9 hours of sleep the AHA recommends for adults. "Around 65% of the cohort actually slept below the recommended time of seven hours a night," said the study's lead researcher Adeep Kulkarni, a data analyst at NYU Grossman School of Medicine in New York City.

Women and participants ages 18 to 44 averaged the most sleep compared to other sexes and age groups. But they still averaged less than the recommended amount.

Of the races studied, white participants, who made up 81% of those studied, generally slept the most, averaging about 6.5 hours a night. Black participants, who made up about 5% of the study group, averaged almost 50 minutes less, getting only 5.7 hours a night.

The 3% of participants who identified as Asian slept an average of 6.3 hours, as did people in the "other" category, who made up about 11% of the study group.

Hispanic people made up roughly 6% of participants and slept an average of about 6.2 hours, compared with 6.5 hours for those who were not Hispanic.

Data from the trackers was paired with the participants' electronic health records. People with high blood pressure, diabetes and sleep apnea averaged slightly less sleep than people without those conditions.

The study's senior researcher, Dr. Souptik Barua, an assistant professor in the department of medicine's division of precision medicine at NYU Grossman, said that while other studies have shown sleep disparities, the new approach provides insights on a scale not previously available.

"For researchers, there have been wearable-based datasets before," Barua said, but the All of Us data "is a game-changer."

Most sleep studies, he said, rely on devices that measure brain waves. Such studies remain "the gold standard," Barua said, but are inconvenient. Sensors must be attached to a participant's face and scalp, and the studies are most reliable when conducted in a sleep lab.

Work with fitness trackers isn't limited to such labs, he said. It's "real life," and can still be estimated relatively accurately compared to the gold standard.

"This is not self-reported or survey data," Barua said. "This is data coming from a device. So that's a more objective measure of sleep."

And while at least has used wrist-worn devices to study sleep, it covered a much shorter period.

"Most studies have analyzed sleep on the order of a week to a few weeks, maybe a month," Barua said. The new work had more than six months' worth of sleep data per person on average.

The ability of the All of Us study team to track sleep patterns for so long was "impressive," said Dr. Julio Fernandez-Mendoza, a professor of psychiatry and behavioral health, public health sciences and neural and behavioral sciences at Penn State University College of Medicine in Hershey, Pennsylvania.

Fernandez-Mendoza, a clinical psychologist who directs Penn State's behavioral sleep medicine program, was not involved in the new work. He said that while sleep disparities between Black and white adults have been well studied using both subjective and objective sleep measures, and other researchers have shown how lack of sleep also plays a role in heart health disparities, the new study's large number of participants and use of commercially available trackers make it unique.

The new study was not designed to explore the root causes of sleep differences, which are wide-ranging, Fernandez-Mendoza said. A 2023 article in noted that socioeconomic status contributes to sleep disparities and that historically excluded groups tend to be disproportionately affected. Factors such as racism and discrimination, psychological stress, financial strain or having to work irregular hours and night shifts all can interfere with sleep.

Barua acknowledged several limits to the new work. Everyone involved had to own a fitness tracker. "It's a younger, more active and predominantly white/non-Hispanic population," he said. It also is a group that would likely be healthier. "So this does not generalize to the U.S. population."

Although most of the tracking data came from after 2013, some of it went back as far as 2009. Sleep tracking technology has evolved over that time, Barua said.

But he said the potential for future studies using such data was high. Already, he said, the All of Us initiative has launched a program to provide trackers to underrepresented communities. And newer devices offer ways to track not only sleep but sleep quality. The amount of deep sleep a person gets has been linked to conditions such as Alzheimer's disease, Barua said.

As more people wear tracking devices, the amount of data available to researchers will only grow, he said. Given how cost-effective it is for researchers to tap such databases, he said, health advice based on such evidence "can be sort of turbocharged."

While his expertise is in data, not treatment, Barua said the findings point to the need for individuals to pay attention to their sleep, given that few get the recommended amount.

People with fitness trackers might use the data to monitor their habits, he said. "That's information that potentially individuals can use to talk to their doctors about."

Find more news from Scientific Sessions.