A startling number of teenagers and young adults are chronically sleep deprived, and the answer is starting school or work later, one sleep expert argues.

According to Paul Kelley, a sleep researcher at the University of Oxford, children between the ages of eight and 10 should start school no earlier than 8:30 a.m., 16-year-olds should start at or after 10 a.m., and 18-year-olds at 11 a.m or later.

The suggestions come from a recent study published by Kelley and his colleagues in the journal Learning, Media and Technology.

"At the age of 10 you get up and go to school and it fits in with our nine-to-five lifestyle," Kelley said Tuesday at the British Science Festival, The Guardian reported. "When you are about 55 you also settle into the same pattern. But in between it changes a huge amount and, depending on your age, you really need to be starting around three hours later, which is entirely natural."

Adults could benefit from a later start, too. People between the ages of 18 and 55 should be starting work at 10 a.m. or later, Kelley added.

Messing with our natural body clock, or circadian rhythms, has been linked to a host of mental and physical problems, including cognitive impairment, anxiety, weight gain, high blood pressure, and diabetes.

The age range where we experience the most sleep deprivation is 14 to 24, when we get about two hours too little sleep per night. From age 24 to 30, we get about 1.5 hours too little, and from 30 to 55, we lose about an hour, Kelley told Business Insider. And the effects are cumulative. "Each day of sleep loss is added on to the next, until have chance to [sleep in]," Kelley said.

Let the teens sleep in

In line with Kelley's advice, the American Academy of Pediatrics recommends that middle and high schools should aim for a start time of no earlier than 8:30 a.m., and the US Department of Health recently published a study in favor of later start times. Research suggests that later school start times can improve daytime sleepiness and mood, but this has not been studied on a large scale in a randomized trial in the UK until now, Kelley said.

Kelley has been working with neuroscientists Russell Foster of Oxford and Steven Lockley of Harvard Medical School to study the effects of shifted school schedules on academic performance.

They are leading a project called Teensleep, which aims to study the effect of later start times at 100 schools throughout the UK among students aged 14 to 16.

During the project, whose results are scheduled to be published by September 2018, each school will be randomly assigned to have either an early or late start time. The researchers will also educate students at some of the schools about healthy sleep habits.

Academic performance will be measured by standardized national tests, which are given to all UK students. To determine if school start time had an effect on test scores, the findings will be analyzed by an independent group of researchers, so as not to bias the results.

Screen addicts and night owls

Of course, the time we start school or work is not the only factor affecting how much quality sleep we get.

The hours we spend exposing ourselves to bright light from our computers, phones and other devices are also eating into our sleep by preventing our brains from producing a chemical, called melatonin, that tells us its time for bed, studies suggest.

Avoiding bright screens an hour before sleep could make a big difference in the amount of sleep we get, Kelley said.

Research has also shown that people's natural sleep cycles, or chronotypes, vary. Some people (called "larks") wake up early and go to bed early, whereas others ("owls") wake up later and stay up late. So although the average teen wakes up later than kids or older adults, not all do.

Still, adjusting school start times for the average teen could be a step in the right direction.