The amount of time the average American spends sitting in front of the TV or computer has increased over the past two decades, shows survey data from 2001–2016. Findings were published in the Journal of the American Medical Association and raise concerns about the effects of sedentary time on cardiovascular health.

Sedentary time—defined as time spent sitting or lying for long stretches of time—has become a growing health concern in recent years. Too much sedentary time has been linked to increased risk for obesity, heart disease, cancer, diabetes, and even risk of death. Between smartphones, televisions, and computers, most Americans are spending more time inactive than ever before.

But just how big of a problem has it become? To learn more, researchers analyzed data from an annual survey on health and lifestyle. The study, called the National Health and Nutrition Examination Survey, routinely asked a sample of Americans about their activity levels—including how much time they spent sitting in front of a TV or computer on an average day.

Surveys were conducted from 2001–2016 and collected data on three age groups—children (5–11 years old), adolescents (12–19 years old), and adults (20 years or older).

In total, 51,896 participants were included in the recent study. Depending on age group, the latest data showed 59%–84% of Americans spent at least 2 hours a day watching TV or videos, with the highest rates among adults aged 65 years or older. Unfortunately, authors note that these rates remained high throughout the study period with little change.

Similarly, too much computer time was also common, with about half of Americans spending at least 1 hour a day on the computer outside of school or work in the early 2000s. By 2016, these rates increased by up to 21%. Researchers also note that over the study period, total sitting time increased from 7 to 8.2 hours a day among adolescents and from 5.5 to 6.4 among adults.

According to authors, these findings suggest that most Americans spent too much time being sedentary, despite warnings about health effects. Data suggest that more than half of children and adults spend hours watching TV or on the computer each day. Based on trends, these rates are not expected to drop anytime soon. As a result, experts encourage research, education, and policies to help Americans cut back on sitting time and increase physical activity.

Current guidelines recommend at least 150 minutes of moderate activity or 75 minutes of vigorous activity a week for adults, and 1 hour of exercise a day for kids. The World Health Organization recommends no more than 1 hour of screen time a day in children, as too much TV time can have effects on both development and overall health. Current guidelines also advise against prolonged sitting in all age groups, as too much sedentary time increases health risks like obesity and heart disease.

Decreasing both screen time and sedentary time can be a challenge in this day and age. However, experts hope that with future efforts, we can help reverse recent trends and improve America’s health.