In simpler times, there was simpler advice for staying healthy: “An apple a day keeps the doctor away.” The proverb can be traced back more than 150 years, when Notes and Queries, a noted academic correspondence magazine, first published a wordier rhyming version in its February 1866 issue: “Eat an apple on going to bed, and you’ll keep the doctor from earning his bread.”

This urging to munch your way to health hung around for decades—until medical researchers slowly began to think more holistically, and consumers began to demand more ways to be proactive about caring for themselves.

Still, once the researchers got involved, the advice seemed to become dizzying at a dizzying pace: Vitamin D was a panacea one week, the next week we were cautioned that we already got too much; coffee was demonized, then embraced for heart health; optimum exercise levels soared and plummeted wildly in the daily news.

Despite the confusion over the healthiest approaches to take, life expectancies in developing nations have continued to increase, with 30 years added to the average in a century. And researchers at the Stanford Center on Longevity recently noted: “Increases continue today, with three months added to life expectancy at 65 every year.”

The Stanford researchers also noted that as the majority of the population lives longer into old age, the acute diseases that usually killed people—such as influenza—have been replaced by chronic ones—such as heart disease, cancer, and diabetes. The underlying good news is that these diseases are largely preventable or can often be kept in check by changes in choices and lifestyles.

They also advocated a shift in priorities: from medicating and doctoring symptoms to urging behavior modifications to increase physical activity, eat better, socialize more, and sleep more soundly.

New Thinking: The 24-Hour Human Activity Cycle

Health advice that’s emerged and encouraged into our time has focused mostly on one thing: the need for people to add more and regular exercise to their daily schedules. But in the new way of thinking, it’s a short-minded fix. That’s particularly true for older people, who often get most of their exercise through lower intensity activities such as gardening, walking, and shopping—activities not generally valued under existing activity guidelines. So despite their best efforts, seniors are consistently made to feel that they’re somehow not doing enough.

Instead of fixating narrowly on a single activity such as exercise, the new way of thinking looks at the totality of the hours in a day: the 24-Hour Human Activity Cycle, or 24 HAC. Each day is envisioned as a 24-hour clock divided into four domains: exercise, sleep, sedentary behavior, and light activity. This allows for tailoring individual health advice attuned to current research on physical activity, which supports the finding that even low levels of activity contribute to better health.

And it allows for important corrections. For example, a person who sits most of the day is able to meet current exercise guidelines as long as he or she puts in 30 minutes at the gym, whereas a person employed as a housecleaner or construction worker who spends most of an exhausting day standing and pushing and pulling heavy objects but logs no “exercise” time is evaluated as coming up short.

Proponents say the 24 HAC is built on decades of research, and is more realistic in accounting for all levels of activity.

Exercise. Touted as the best understood and most researched of the domains, exercise has long been linked to improvements in a range of conditions—including heart disease, cancer, obesity and diabetes, as well as fostering brain health and decreasing symptoms of clinical depression. The most recent guidelines, supported by both the American Heart Association and American College of Sports recommend that individuals get at least 150 minutes of moderate exercise or 75 minutes of vigorous exercise weekly.

Sleep. The importance of sleep has been hailed since ancient times, though why and how it helps keep people healthy remains somewhat of a puzzle. What’s been well-studied and accepted is that the lack of sleep can cause a host of health complications—including heart disease, high blood pressure, and strokes. While acknowledging that the number of nightly hours an individual “needs” is most related to genetics, the American Sleep Association recently recommend a few age-related guidelines: 7 to 9 hours of sleep for people 61 to 64 years old and 7 to 8 hours for those 65 and older.

Sedentary behavior. The latest health-related call to action is to stand and walk periodically rather than stay seated for long periods of time—though it’s a call that’s commonly ignored. Still, sitting has recently been recognized as a risk factor for heart disease, obesity, and diabetes—prompting a call (also ignored so far) for national guidelines on sitting. Researchers concluded one study with the commonsense observation and plea: “Most people now agree that secondhand smoke is to be avoided, but people had no such concerns until recently. Most thought the Marlboro Man was the picture of good health. We would suggest that, in the future, too much sitting might be considered in the same way as have other such insidious environmental and behavioral health hazards.” Proponents of 24 HAC agree that the lack of guidance on the “appropriate” amount of sedentary activity in a day is the biggest challenge in its model.

Light activity. The category of “light activity” is a sort of catch-all for whatever is not defined as exercise, sleep, or sedentary behavior. In reality, it probably makes of the majority of the day for most people, especially seniors, whose movement and exercise often don’t meet “traditional” definitions of sweat-drenching exercise such as running or lifting weights.

Wearables Were the Inspiration

The new approach to the old problem of optimal health recommendations came from an unlikely source: consumer “wearables” that measure and monitor physical activity, sleep, and time spent in sedentary behavior throughout the day. The number of such wearables is burgeoning; a website that tracks just some of these trackers tallies 429 badges, watches, gloves, and belts measuring everything from heart rate to blood oxygen saturation to brainwaves.

Technology and medicine have tended to clash rather than collaborate, but that may be changing with the recognition that real-time data can be used to urge real-life changes.

“Through technology, we’re recognizing that our day is not counted by 30 minutes of exercise, but knowing that the entire day counts, and every piece in these domains has relevance to your actual health,” says Ginna Baik, senior care practice leader at CDW Healthcare,  which provides technology solutions to healthcare providers. “That’s why wearables are no longer a fad, they’re valuable measurement tools.”