Sleep Zone

Why teens sleep later

Most parents of teenagers remember a time when their child used to wake up early. There is a clear change in sleep timing in the teenage years, with children going to bed later, struggling to wake in the morning and sleeping later at the weekends. Why is this?

The drivers of sleep

Sleep is regulated by two systems in the body. Firstly, there is the circadian rhythm. This is an internal body clock which controls the timing of many bodily processes, including the release of a hormone called melatonin. Melatonin is a hormone produced in the brain to tell you it’s time for sleep. During the day, melatonin is suppressed, but in the evening, in dim lights it will start to be released. The clock is set to a 24-hour cycle but the timing of the clock varies from person to person, so we get sleepy at different times and the time we naturally wake is not the same.

The second system is the homeostatic sleep drive. This system works like a pressure cooker: when you are awake, sleep pressure builds up due to a metabolite called adenosine, a by-product of energy production. This sleep pressure becomes stronger the longer you are awake. Then when you sleep, the pressure is relieved, like steam being released from the valve of a pressure cooker.

These two systems work together to give you the right amount of sleep at the right time. Teenagers need more sleep than adults, with sleep experts recommending 8-10 hours every night. However, many teenagers struggle to get enough sleep due to the changes that occur to the biological drivers of sleep. During adolescence, hormonal changes affect these systems and the timing of sleep. The circadian rhythm becomes delayed so the release of melatonin happens later in the evening. In addition, the homeostatic sleep drive builds more slowly. Both these changes result in teenagers not feeling sleepy until later and finding it hard to wake up early in the morning.

Exacerbating factors

It’s important to understand that this change in sleep timing is driven mainly by biology. However, the picture is more complex because there are environmental influences that will exacerbate the problem. The timing of the clock is strongly influenced by the timing of light. The clock expects darkness at night and this allows the release of melatonin. The circadian rhythm needs light in the morning and during the day to keep it to time, as well as a reduction in light intensity during the evening.

When teenagers don’t feel sleepy in the evening, they want something to do. They often reach for their phone which is a light-emitting device. There are receptors behind the retina which can detect the brightness of light and this information is sent to the area of the brain where the “master” body clock sits. So light-emitting devices held close to the eyes have the ability to push the body clock later if used late at night. In addition, using a phone at night is a stimulating activity; social media, games and browsing keeps the brain alert. Before sleep it’s advisable to do non-stimulating activities like reading or listening to music to wind down.

The timing of when you eat is another “zeitgeber” or time keeper for the circadian rhythm. Eating breakfast helps to kick start the circadian rhythm. However, it’s common for teenagers to skip breakfast as they don’t have time in the morning and don’t feel hungry. The circadian rhythm also influences appetite so with a delayed circadian rhythm comes a lack of hunger in the morning. However, skipping breakfast and eating late into the evening can cause the circadian clock to drift later.

Most teenagers have to wake up for school far earlier than their natural body clock would dictate. This, combined with late nights, results in teenagers not getting enough sleep during the week. Several studies have shown that starting school later in the morning results in better academic performance, improved attendance, more sleep and better health outcomes, with little evidence that this results in later nights. The evidence is so strong that both the American Academy of Pediatrics and the Centers for Disease Control and Prevention have advocated for delayed school start times for adolescents.

What can parents do to help teenagers to get enough sleep?

It can be helpful to explain to teenagers how the sleep drivers change during adolescence. This acknowledgement can validate their experience: that they are not necessarily trying to go to bed late but are just not sleepy. Equally they are not being lazy in the morning but are really struggling to wake up early.

Agree a set bed time, eight to ten hours before the time they have to wake. Some research shows teens get more sleep if their parents set a firm bedtime. Try not to deviate too far from this bedtime at the weekend and reduce Sunday lying in to just an hour more than usual.

Encourage them to not use their phone in their bedroom or to put it on flight mode at least one hour before bed, explaining the rationale for this. Discuss alternative ways to wind down before sleep like reading a book or magazine or listening to something with the lights low. Discourage homework too late into the evening, allowing at least an hour to wind down.

Explain how caffeine can cause problems getting to sleep if drunk too late in the afternoon or evening and provide alternatives (although not ideal, non-caffeinated fizzy drinks at least will not affect sleep).

Getting outside in the morning can really help to promote sleep later so walking to school is a good idea, if possible. If not, some outside time in the morning is advisable, such as breakfast outside.

Anxiety and problems with mood can negatively affect sleep so be there to talk about any stresses or problems your child is going through. Speak to a doctor if you feel mental health problems are behind any sleep issues.

Rather than setting rigid rules for them, encourage teenagers to take ownership of these behaviours by explaining why sleep is important and the effects of sleep deprivation. Sleep affects so many things so choose what is important to your child: health, mood, academic performance, athletic ability.

Christabel Majendie August 2022.

Christabel is a Bristol based sleep therapist and consultant, specialising in helping individuals experiencing a wide range of sleep problems. For more information on her work you can visit her website.

Christabel is not a brand ambassador and does not endorse any product of Sleep Well Drinks Limited.