Teenagers who regularly change their sleeping patterns between weekdays and weekends may face a greater risk of anxiety, according to a new study from researchers at the University of Southampton in the United Kingdom.

The findings come as students return to school after the summer break, when many adolescents may have become accustomed to later nights and longer mornings. The shift back to early school schedules can create a mismatch between weekday and weekend sleep patterns, a phenomenon researchers describe as “social jet lag.”

A review of 12 studies involving more than 230,000 participants found that teenagers experiencing greater levels of social jet lag were more likely to report higher levels of anxiety. The relationship also appeared to work in the opposite direction, with higher anxiety associated with greater disruption to sleep schedules.

However, researchers stressed that the findings show an association rather than proving that irregular sleep directly causes anxiety.

The study highlights the importance of encouraging healthy and consistent sleeping habits as part of efforts to support adolescent mental health. Anxiety is already one of the most common mental health problems among young people.

The World Health Organization estimates that anxiety disorders affect about 4.4% of children aged 10 to 14 and 5.5% of those aged 15 to 19 worldwide. Such disorders involve persistent fear or nervousness that can be difficult to control.

Researchers say adolescence is a particularly important period for sleep because biological changes naturally alter young people’s body clocks.

Sarah Chellappa, a co-author of the study from the University of Southampton, said teenagers generally experience a shift toward later sleep during puberty.

“During puberty, the body’s internal clock usually shifts back by a few hours,” she said, meaning teenagers naturally become sleepy later and may need to wake later as well.

Early school starts can conflict with this biological change. Social activities, online communication and other demands can also reduce the amount of sleep teenagers get during the week.

Hannah Ravenhall, lead author of the study, said the issue should not be viewed solely as a matter of individual responsibility.

She said broader social systems can influence young people’s sleep and called for greater recognition of the biological changes that occur during adolescence.

The researchers suggested that schools could consider whether their start times adequately reflect teenagers’ changing sleep needs. Parents could also review evening routines, including rules around screen use.

Rather than simply encouraging teenagers to go to bed earlier, the researchers argue that more consistent schedules and changes to the environments in which young people live and study could help support better sleep and mental wellbeing.

Novo Nordisk’s Wegovy weight-loss pill has gone on sale in German pharmacies, giving adults an alternative to the weekly injection already used to treat obesity.

The prescription-only tablet became available in Germany on September 1 following approval by European regulators in July. Germany is the first European country where the oral version of Wegovy is being marketed. Novo Nordisk described the launch as a major milestone for its obesity treatment business.

The tablet contains semaglutide, the same active ingredient used in the injectable form of Wegovy. The medicine works by mimicking a gut hormone involved in regulating appetite and increasing feelings of fullness, which can help people eat less.

Novo Nordisk expects the retail pharmacy price for the adult tablet to range from about €170 to €280. Unlike the injectable version, which is approved for some children aged 12 and above, the tablet is currently authorised only for adults.

Evidence supporting the European approval came largely from the OASIS-4 clinical trial. In the study, 205 participants received the semaglutide tablet, while another 102 were given a placebo. Adults taking the medicine lost an average of about 13.6 per cent of their body weight during the 64-week treatment period.

The weight reduction was lower than that recorded with injectable semaglutide in a separate study, where participants lost an average of 19 per cent. However, the injection trial lasted 72 weeks, giving participants eight additional weeks of treatment.

The tablet also carries potential side effects. Gastrointestinal problems such as nausea and diarrhoea are among the commonly reported reactions. In some cases, semaglutide can also cause inflammation of the pancreas.

The main difference for patients is how the medicine is taken. The tablet must be taken every day, while Wegovy injections are administered once a week.

Julia Szendrödi, president of the German Diabetes Association, said medication should be used alongside healthy eating and physical activity. She stressed that obesity treatments are designed to form part of a wider approach to managing a chronic disease rather than serving as a quick solution for weight control.

Szendrödi also called for stronger prevention measures, including clearer food labelling, improved nutritional standards for school meals and restrictions on advertising unhealthy food to children.

The launch comes as pharmaceutical companies compete for a rapidly expanding global obesity-drug market. Analysts expect the sector could generate about $100 billion in annual sales by 2030.

Novo Nordisk faces growing competition from rivals including Eli Lilly, which is expanding its own oral weight-loss treatment portfolio. In the UK, Eli Lilly’s Foundayo pill is scheduled to become available.

Wegovy and similar medicines are primarily intended for people with obesity, generally defined as a BMI of 30 or higher. They may also be prescribed to some people with a lower BMI when excess weight is linked to conditions such as type 2 diabetes or sleep apnoea.