The COVID-19 pandemic has taken a significant toll on people's mental health, and young people are a particularly affected group, with school closures cutting off millions of both young and older children from their friends, teachers, and any semblance of normal life.

The negative psychological effects of this have been documented in many studies, but by at least one measure, school closures also seem to have had at least one significant positive effect on students too.

In a new study from Switzerland, researchers found Swiss teenagers who were home-schooled during school closures between March and June 2020 in the first wave of the pandemic ended up getting significantly more sleep than before the lockdown, which correlated with other improvements in their wellbeing.

"The students got about 75 minutes more sleep per day during the lockdown," says developmental pediatrics researcher Oskar Jenni from the University of Zurich (UZH).

"At the same time, their health-related quality of life improved significantly and their consumption of alcohol and caffeine went down."

In the study, Jenni and fellow researchers conducted an online survey of over 3,600 high school students from the Zurich region, with questions that asked them about their sleep patterns, along with other questions that related to health and behavioral characteristics.

The results were then compared with a previous survey of over 5,300 students conducted in 2017, long before the COVID-19 pandemic began.

The comparison showed that during the school week, the home-schooling group woke up around 90 minutes later on average than the teenagers in the control group; however, they also went to bed around 15 minutes later, meaning in total their sleep surplus was about 75 minutes each day.

At the same time, some of the lockdown group's health-related and behavioral characteristics were improved compared to the control group, suggesting the extra 75 minutes of daily sleep made them feel better about some things – even though other effects of the isolation in the pandemic could also be observed in the responses.

"Higher values were indicated by the lockdown sample on the items for feeling fit and well, for being full of energy, for having enough time for themselves, and for being able to do the things they wanted in their free time," the researchers write in their paper, led by first author and UZH neuropsychology researcher Joëlle N. Albrecht.

"Conversely, adolescents in the lockdown sample indicated feeling lonelier and sadder and having less fun with friends."

According to Jenni, the results show that while the isolation effects of home-schooling during lockdown had some negative repercussions on teenagers, that extra amount of sleep did appear to deliver benefits that made stuck-at-home days more tolerable in the long run.

"Although the lockdown clearly led to worse health and well-being for many young people, our findings reveal an upside of the school closures which has received little attention until now," Jenni says.

"Our findings clearly indicate the benefit of starting school later in the morning so that youngsters can get more sleep."

On that count, at least, we probably shouldn't be too surprised. For several years now, numerous studies have shown evidence that the school day should start later, with teenagers getting extra-shut eye due to later school start times showing improved alertness and wellbeing, in addition to reporting better sleep and ability to concentrate and study.

Some experts even think late teenagers shouldn't start the school day until 10 am or even 11 am. The new study isn't quite so prescriptive, but it's yet more data to support the argument that children can benefit from starting their learning later in the day, even in the isolation and hardship of a pandemic lockdown.

"The findings suggest that school closures allowed students to better align their sleep schedules with adolescents' late sleep phase," the researchers explain.

"Of most importance, to our knowledge, this study provides the first scientific evidence for the beneficial sleep-related associations of school closures with adolescents' health."

The findings are reported in JAMA Network Open.