In "Sleep deprivation" (By the numbers, 4 October), you assert that "hormonal changes affect teenagers' body clocks".
I have three teenagers, and anecdotal evidence suggests that the increased autonomy associated with growing up, combined with a lack of self- discipline (and possibly too much laissez-faire parenting), is the main driver behind teenagers going to sleep later, and consequently waking up later.
Teenagers have too many exciting things to do at night. Short of confiscating their mobile phones, switching off the wi-fiand cutting the power to the PlayStation and television, I am not sure what we can do to remove such temptations.
Teenagers need to adapt to their environment and learn to go to sleep earlier so they can wake up in time for school, just as adults must get up early enough to avoid capability proceedings at work. Schools that take this vital life skill seriously should continue to ask their students to turn up before 9am. Schools that decide to delay starting times do young people no favours by pandering to the myth that hormones are the only factor here and abstaining from their responsibility to prepare students for the real world.
I would welcome any references you have to research containing robust evidence that hormones affect body clocks. For now, I remain unconvinced.
Russell Bowen, Parent of teenagers.