Lessons will start at ten in three schools from January.

Pupils at three secondary schools in Calder and the valley will start lessons at 10am from the first week of January, in a trial designed to test whether letting teenagers sleep later improves their health, mood and exam results. The schools – Northgate Academy in the city, Ardle High School and Kelderby Community School in the hill towns – will keep the later timetable for at least two full terms.

The trial applies to pupils aged fourteen to eighteen. Younger year groups will keep their current start time of around 8.45am, partly because younger children’s sleep patterns differ and partly to allow comparisons within each school. The school day for older pupils will finish at 4.30pm instead of 3.15pm, with a shorter lunch break to compensate.

The biology behind the change

During adolescence, the body releases the sleep hormone melatonin up to two hours later in the evening than it does in childhood or adulthood. That shift means many teenagers genuinely cannot fall asleep before 11pm, however early they go to bed, and need eight to ten hours of sleep to function well. With school starting before 9am and a bus to catch, many are getting closer to six.

“We are asking teenagers to sit maths exams at a time their brains believe is the middle of the night. If an adult worked those hours, we would call it shift work and worry about the effects.”

Dr Anwen Folarin, a sleep researcher at Calder University who designed the trial with the region’s education department, said studies elsewhere had found that later starts led to around 30 to 45 minutes more sleep a night on average, with improvements in attendance, attention and mood. She stressed that results vary, and the purpose of the trial is to see whether those findings hold in Calder’s schools, with their particular transport and family patterns.

What parents and pupils have been told

Letters sent home last week set out the practical details. Breakfast clubs will continue from 8am for pupils who need to arrive early, and the library and study rooms will be staffed from 8.30. Buses serving Ardle and Kelderby will be retimed to arrive at 9.40, after the regional transport authority agreed to move four morning services. After-school clubs and sports fixtures will begin at 4.45, and the schools have negotiated with local leagues to push some weekday matches later.

Some parents have raised concerns. Families with younger children at other schools face two separate morning runs, and parents working early shifts worry about teenagers being left alone in the house. Jonah Whitlock, who chairs the parents’ forum at Northgate and has a son in Year 10, said reactions were mixed but mostly curious. “Half the parents think it is overdue,” he said. “The other half want to know who will make sure they actually get out of bed at nine.”

Teachers’ unions have agreed to the trial on the condition that no member’s working day is extended, which means rotas have been redrawn to stagger arrival times. A handful of teachers with childcare responsibilities have moved to teach only younger year groups for the duration.

How success will be measured

Around 1,800 pupils will take part, and about 400 of them have volunteered to wear wrist devices that record when they fall asleep and wake. Researchers will also track attendance, punctuality, behaviour records and the results of mock exams, comparing them with pupils in four similar schools that keep their normal timetable. Pupils will complete short questionnaires on mood and wellbeing at the start, middle and end of the trial.

A first report is expected in the autumn. If the results are positive, the education department has said it will consider extending later starts to other schools from the following year, although officials acknowledge that transport costs, rather than educational arguments, are likely to decide how far and how fast any change can go.