Nutrition and your teens circadian rhythm

Nutrition and your teens circadian rhythm

Is your teen constantly tired, but on their phone until late at night despite your best efforts? Scientists have found evidence that teens’ circadian rhythm–or natural sleep cycle–is delayed by as much as two hours compared to adults’. The reason for this delay isn’t fully understood, but it may be due to changes in hormone levels and how these hormones affect melatonin production. So what can be done about it? Let’s explore in more detail…



Your circadian rhythm is the physical, mental and behavioural changes that follow a 24-hour cycle¹. Two main examples of this include our sleep-wake cycle and the related fasting-feasting cycle.  Biological clocks, on the other hand, are our natural timing devices present in almost every cell in the body, that regulate your circadian rhythms. These cycles are genetically coded and produce a variety of proteins that interact with all the cells in the body. Many of the changes experienced due to the circadian rhythm are influenced by the release of certain hormones.

The cells in our brains (specifically the hypothalamus) respond to light or dark telling us when we should be sleepy or not. In response two main hormones are secreted, melatonin to help us sleep and cortisol to wake us up. These hormones alter your body temperature as well: lowering it during nighttime hours to promote restful slumber while raising them in the mornings so you can get going without feeling sluggish or groggy.

Metabolism and gastro-intestinal function are also affected. Hormones like insulin, leptin and ghrelin affect our appetite as well as the body’s ability to store/ utilise energy². Appetite is usually lowest in the morning and highest in the evening. This may be why some people find it very easy to skip breakfast but then tend to overeat at night. Gastro-intestinal function is sped up in the morning, which is why many people go to the toilet first thing (or typically after your first cup of coffee).



Melatonin secretion starts about 2 hours before your regular bedtime and its job is to prepare you for sleep. Teenagers experience a shift in their circadian rhythm that affects this bedtime. Their melatonin doesn’t start to rise until 10 or 11pm meaning that they will typically only get tired much later. Most teens need 9-10 hours of sleep, so in light of their late bedtime, it’s no wonder that many of them struggle to wake up early for school or sleep in very late on the weekends. In actual fact, their peak sleep hours are between 3-7am, so waking earlier than this can be physiologically difficult for them and usually they don’t feel fully ‘awake’ until 9 or even 10am.

To make matters worse, it is even harder for teenagers to fall asleep after their brains are left stimulated from late night homework or from using social media/ playing video games. The blue light from electronic devices like computers, tablets and phone’s can trick the brain into delaying melatonin secretion, pushing their natural bedtime even later. This can lead them into trouble with friends and family who expect them to be awake during normal waking hours.

Simply put, teens are just not tired until late at night and are expected to wake up early, meaning that many of them are missing out on crucial sleep. The benefits of good sleep are wide-ranging from memory recall and focus improvement all the way down to appetite regulation and even weight control. So understanding how to regulate your circadian rhythm to promote sleep is paramount to good health. But, how can we do this?



The effect that your circadian rhythm has on your appetite hormones primes you to feed at specific times. Think about it, most people are hungry during the day and then go to sleep without waking up to eat. Your body thrives off regularity on both a molecular and behavioural level³. Eating at inappropriate times, like very late at night, can disrupt the circadian rhythm and cause you to form bad habits. Each time you eat ‘off schedule’ you are forcing your biological clocks to reset themselves and reinforcing this inappropriate behaviour, making it difficult for your body to keep up with what you are feeding it. Multiple studies have shown that eating in your active phase (i.e. earlier in the day/ during light hours) can promote stable blood sugar levels and weight maintenance.

Your choice of food also makes a difference. Eating more ultra-processed, high fat foods can lead to an unintentional increase in energy consumption during the rest phase. One study found that this increase could add up to more than 500kCal per day! This increase in calories can lead to unwanted weight gain and related health problems.



Teenagers are more susceptible to delayed sleep phase disorders (DSPD)⁴. This condition, commonly called the ‘night owl’ syndrome, is characterised by going to bed late and rising later or feeling perpetually jetlagged.

DSPD and insufficient sleep can:

  • Increase the risk for depression
  • Reduce ability to cope with stress
  • Negatively impact academic performance (affecting memory and focus)
  • Lead to low energy levels
  • Increase risk of gastro-intestinal disorders like constipation, diarrhoea and peptic ulcers
  • Increase appetite (leading to an excessive intake of energy dense foods and subsequent weight gain) and
  • Reduce glucose tolerance (increasing the risk for obesity and type 2 diabetes)

As little as 2 nights of poor sleep can exacerbate these symptoms and so early diagnosis and treatment is essential.



  1. Follow a daily routine. Have a regular bedtime and wake time (even on the weekends) and avoid napping, especially in the afternoon/ early evening.
  2. Eat your meals at regular times, if you eat breakfast, eat breakfast everyday and at about the same time. Same applies to your other meals.
  3. Don’t eat late at night (sorry, no more midnight snacks!)
  4. Avoid/ limit caffeinated beverages like coffee and energy drinks, especially later in the day.
  5. Consider taking a supplement that contains proven sleep related nutrients, like Bioteen Supersleep, at night.
  6. Spend time outdoors, in natural light and remember to exercise regularly.
  7. If necessary, use light therapy in the morning to help wake up.
  8. Optimise your sleep environment (low light, comfortable temperature, supportive bed etc).
  9. Avoid screen time before bed, rather read a book.



Knowing that your teen’s sleeping habits are driven more by biology than ‘bad behaviour’ can help both you and your teen work together to optimise and regulate these patterns, rather than fight them. Not only will this help in the short term, but it will nurture healthy habits which will be easy to carry through into adulthood. A supplement like Bioteen Supersleep can form a nutritional basis for a good night sleep and should be used in conjunction with the information and tips given above for best results.



  1. Gregory, D, Potter M et al. Nutrition and the circadian system. British Journal of Nutrition. 2016, 116, 432 – 442.
  2. Gnocchi D and Bruscalopi G. Circadian Rhythms and Hormonal Homeostasis: Pathophysiological Implications. March, 2017. Circadian Rhythms and Hormonal Homeostasis: Pathophysiological Implications (
  3. Chaix A, Manoogian ENC et al. Time-Restricted Eating to Prevent and Manage Chronic Metabolic Diseases. Annual Review of Nutrition. Vol 39; 291-315.
  4. Bartlett D, Biggs SN and Armstrong SM. Circadian Rhythm disorders among adolescents : assessment and treatment. 2013; 199; 516 – 520. (
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