Delaying school start times in the UK is unlikely to reduce sleep deprivation in teenagers, research from the University of Surrey and Harvard Medical School has found. The research, conducted in collaboration between mathematicians and sleep scientists, predicts that turning down the lights in the evening would be much more effective at tackling sleep deprivation.

Teenagers like to sleep late and struggle to get up in time to go to school. The commonly accepted explanation for this is that adolescents' biological brain clocks are delayed. It has been suggested that to remedy this, school start times should be delayed for older teenagers so that they are again in tune with their biological clock.

The study, which is published today in Scientific Reports, used a mathematical model that takes into account whether people are naturally more of a morning or evening person, the impact of natural and artificial light on the body clock and the typical time of an alarm clock, to predict the effects of delaying school start times.

The mathematical understanding of biological clocks suggests that adolescents are particularly sensitive to the effects of light consumption. However, the model can be applied to other age-groups as well. It can be used to design new interventions not only for sleepy teenagers but also for adults who suffer from delayed sleep phase disorders or people who are not synchronized to the 24-hour day at all.

The research draws attention to light, light consumption and darkness as important environmental and behavioral factors influencing health. This has implications for how we design the light environment at work and at home in our modern light-polluted societies.