A study suggests most would be able to wake easily if they went outside more, then dimmed lights and stopped using smartphones and tablets at night.

Morning is known to be their least favourite time of day.

But teenagers struggling to get out of bed on time is nothing to do with their hormones or a need for extra sleep, researchers say.

A study suggests most would be able to wake easily if they went outside more, then dimmed lights and stopped using smartphones and tablets at night.

Surrey University and Harvard Medical School scientists found artificial light may be wholly to blame for Western teenagers rising late. Adolescents in hunter-gatherer tribes, who are outside all day and see light change naturally, get up at dawn. 

The study, in the journal Scientific Reports, looked at 25 000 Europeans and two African tribes. It found teens were the age group most affected by light, and turning off blue light screens and dimming other lights could reset their body clocks.

Author Dr Anne Skeldon said teenagers are "not 'programmed' to wake up late… increasing exposure to bright light during the day, turning lights down in the evening and off at night should enable most to get up in time".