Circadian rhythm

I am neither an early bird nor a night owl. I like to be in bed by 10.30pm, and if I could choose I would wake up naturally at 8.30am. Despite this, I have days where I start teaching at 6.45am.

In all my years of teaching I have learned that, generally:

• teenagers do not function well in the mornings
• grammar is best taught to adults in the morning
• bad times to teach adults  things that need a lot of brain power are: just before lunch, just after lunch, before the morning coffee break, and just before end of day.

I have discussed individual circadian rhythm with my students, and they prefer workplaces with flexible working hours. I have one student I have been teaching for 25 years who starts work at 9.30am and finishes at about 7.30pm. Despite her long working hours and being the hardest worker I know, she says that people tend to believe she is lazy, due to her not being at her best in the early morning and starting work later. I have mentioned this to other students who are at their best later in the morning, and they tend to agree. Society is built on an 8 or 9 to 5, and anyone outside that box is ‘not normal’.

There was a 2014 report that said

When children are around ten, their biological wake-up time is about 6.30am; at 16, this rises to 8am; and, at 18, someone you may think of as a lazy teenager actually has a natural waking hour of 9am. The conventional school starting time works for 10-year-olds but not 16- to 18-year-olds. For the older teenagers, it might be more sensible to start the school day at 11am or even later. “A 7am alarm call for older adolescents,” Kelley and his colleagues pointed out in the paper, “is the equivalent of a 4.30am start for a teacher in their 50s.”

He says it’s not as simple as persuading teenagers to go to bed earlier. “The body’s natural rhythm is controlled by a particular kind of light,” says Kelley. “The eye doesn’t just contain rods and cones; it contains cells that then report to the suprachiasmatic nuclei in the hypothalamus.” This part of the brain controls our circadian rhythms over a 24-hour cycle. “It’s the light that controls it. It’s like saying: ‘Why can’t you control your heartbeat?’”

But it isn’t just students who would benefit from a later start. Kelley says the working day should be more forgiving of our natural rhythms. Describing the average sleep loss per night for different age groups, he says: “Between 14 and 24, it’s more than two hours. For people aged between 24 and about 30 or 35, it’s about an hour and a half. That can continue up until you’re about 55 when it’s in balance again. The 10-year-old and 55-year-old wake and sleep naturally at the same time.”

This might be why, he adds, the traditional nine to five is so ingrained; it is maintained by bosses, many of them in their mid-50s and upwards because “it is best for them”. So, should workplaces have staggered starting times, too? Should those in their 50s and above come in at 8am, while those in their 30s start at 10am and the teenage intern or apprentice be encouraged to turn up at 11am? Kelley says that synchronized hours could have “many positive consequences. The positive side of this is people’s performance, mood and health will improve.

In addition, there are theories about the existence of the different circadian rhythms in humans being an evolutionary benefit of having them in a community. Having some members of a group naturally awake at night was a big advantage 200 000+ years ago when someone had to guard a settlement from predators and other dangers.

Luckily, Sweden allows for flexible working hours, and is very parent-friendly, allowing for daycare drop-offs and pickups. It is not unusual for people to leave work at 3pm to pick up children. Swedes are also very hard workers so there is not much slacking off.