A new study from journal publisher Taylor & Francis reveals youth’s irritability and laziness aren’t due to attitude problems but to lack of sleep.

Recently published in the journal of Learning, Media and Technology, a paper exposes the negative consequences of sleep deprivation caused by early school bells, and shows that altering education times not only perks up teens’ mood, but also enhances learning and health.

It is no secret that human biology and education measure time in different ways, but “our ability to function optimally [and learn], varies with biological time rather than conventional social times,” says the team leading the research in a release.

When the two are more closely aligned, like in early years education, this is not so critical.

But things drastically change during adolescence, when “the conflict between social and biological time is greater than at any point in our lives,” continue the academics.

The sleep-wake cycle, or circadian rhythm, is the result of a complex balance between states of alertness and sleepiness regulated by a part of the brain called the suprachiasmatic nucleus (SNC). In puberty, shifts in the body clock push optimal sleep later into the evening, making it extremely difficult for most teenagers to fall asleep before 11 PM.

This, coupled with early morning school starts, results in chronically sleep-deprived and cranky teens, as well as plummeting grades and health problems.

There is a body of evidence showing the benefits of synchronizing education times with teens’ body clocks. Interestingly, while “studies of later start times have consistently reported benefits to adolescent sleep health and learning, there [is no evidence] showing early starts have a positive impact on such things,” say the researchers.

In spite of examples corroborating this theory—crucial is the case of the United States Air Force Academy, where a later start policy has been instrumental in improving the marks of a group of 18 to 19 year olds—educators still fail to grasp it’s not laziness that keeps teens in bed in the morning but their biological clocks.

However, regardless of reluctance to alter the way things have always been done, a number of initiatives—including the Start School Later campaign and the establishment of the National Sleep Foundation—indicate a change may be in the air for education policies and practices in the United States.

“Good policies should be based on good evidence and the data shows that children are currently placed at an enormous disadvantage by being forced to keep inappropriate education times,” argue the team.