The basic fact that teens have a different sleep pattern to other age groups is true - the human circadian rhythm shifts around two or three hours during the teenage years, so they will want to go to bed later and get up later. 

Also true is that this means getting up for school is harder for teens than younger children, as when school starts they naturally want to be in bed. 

But how true is it that disrupting a teenager’s shut-eye has a negative impact on their schooling?

Sleep and school start times

As we explore in the video below, stage-2 sleep (which occurs primarily during later sleep cycles) is essential for memory formation. Unfortunately, owing to the biological mechanism of Sleep-Phase Delay and the time schools expect teens to be in, most teenagers don’t spend a lot of time in this stage-2 sleep.  

This almost certainly impairs memory formation during adolescence.

But are the logistical challenges of shifting the school start times for teens proportional to the potential damage of interrupting their sleep?

Science of sleep

A common worry among opponents of a later school start time is that teenage students will spend any additional time-at-home playing video games, watching films, or chatting with friends - not catching up on sleep.  

Luckily, the research doesn’t bear this out. Many studies have demonstrated that when school starts later, teenage sleep duration increases by approximately 8 minutes for every 15 minutes of delayed start time. In other words, they are using the extra time at home to catch up on sleep.

Beyond sleep duration, delaying the school start time has been demonstrated to lead to significantly less daytime drowsiness, classroom napping, and caffeine consumption among adolescent students.

In addition, several studies have demonstrated a significant positive correlation between later school start times and student grades.  

Sleep and schools

However, there does not appear to be a correlation between school start time and standardized test performance. This suggests that delayed starts may impact the type of deep, sustained learning commonly favoured within classrooms but rarely tested on national or international exams.

Furthermore, research has demonstrated a negative correlation between delayed school start time and student absence and tardiness. 

So it’s a mixed picture. And if we focus on other aspects, we see that mix once more. 

Depression and wellbeing

For example, sleep is strongly linked with many cognitive and mental disorders. With this in mind, there is evidence to suggest that students in later-starting schools experience significantly fewer depressive symptoms than students in earlier-starting schools.  

Furthermore, delayed school start times have been correlated with reduced negative affect and more positive emotions.

However, it’s important to remember that teenagers aren’t the only stakeholders in education. When considering extracurricular activities, a later school start time means some teachers will be stuck at school until 6-7pm each night. Also, when considering commute time, a later school start means some parents might struggle to arrive at work on time.  

Finally, when considering the fact that younger children do not suffer from sleep-phase delay, a later school start time would likely disrupt learning among primary students.

In the end, the number of stake-holders and involved logistics might outweigh the consideration of teenage memory consolidation.  

Regardless, it’s important that the final determination of school start time is made using clear and explicit reasoning. Although the evidence can never tell us specifically what to do, it can offer meaningful ideas we can use to guide and justify our final decisions.

Jared Cooney Horvath is a neuroscientist, educator and author. To ask our resident learning scientist a question, please email: AskALearningScientist@gmail.com