The American Academy of Pediatrics and the National Sleep Foundation recommend that school-aged children (6-13) sleep between 9-11 hours per night, while older teenagers (14-17) are advised to sleep between 8-10 hours per night. 

For adults, the recommendation narrows to between 7-9 hours per night. 

 

For teens, there are two important factors that contribute to sleeping less.  The first is biological, and is related to the changes in brain’s circadian clock that occur as puberty approaches. Beginning in early adolescence, youth have a biological tendency to go to sleep later and later in the evening, and have an increased propensity for later morning awakenings.  Basically, this circadian process works to turn teens into ‘night owls’. However, another important factor is engagement in unhealthy sleep behaviors or what’s called poor “sleep hygiene”. This includes irregular sleep–wake patterns (e.g., not going to bed and waking at the same time every day), electronic media use in the bedroom, and excessive caffeine consumption. The electronic device issue is an important one because the blue that is emitted from electronic devices, including computers, phones and TVs further compound the circadian shift in sleep timing; The short waves of blue light suppresses a hormone called melatonin, which is one of the important signals that tells circadian clock its sleep time.  So, basically, not only does using your phone late at night keep you up acutely, it also shifts your circadian clock by telling it that it is early in the day and not time for sleep. 

 

For most adolescents, school still starts in the early morning and, as a consequence, may exacerbate sleep loss in teens. All the reasons above, particularly electronic media use at the wrong time of day also play a role. 

 

Insufficient sleep has enormous consequences on mood and cognitive function, which is my area of research.  Insufficient sleep does two things to learning: Under conditions of sleep restriction like that typically seen in American teens, the brain is less able to learn, or take in information.  Sleep acts like a ‘reset’ button for the brain. A brain that learns all day becomes saturated, and sleep is necessary to effectively reset neurons to allow room for more information.  In addition, sleep plays an active role in the process of memory consolidation, so without sleep, the things you’ve learned aren’t cemented in your brain optimally.  Although sleep’s role in memory consolidation is studied for all kinds of learning, one area where it’s particularly easy to see, and has been extensively studied, is in motor skill learning-- the kind of learning that happens automatically when playing a sport or musical instrument.  So, if you want to be a great tennis player or cellist, you need to sleep!  

 

Sleep is also essential for optimal emotional function.  We know that sleep loss contributes to increased emotional reactivity or liability in all ages, but this is particularly true for young kids and teens. Sleep loss is also associated with impaired judgement and increase propensity for risk taking—a phenomenon that contributes to drug and alcohol misuse in teens.  In addition to the acute or immediate impacts of sleep loss, we also know that sleep, particularly slow-wave sleep, functions to support the reorganization of brain circuitry. During adolescence, the brain is still undergoing quite dramatic structural and functional changes; In fact brain development extends into the early 20s for girls and mid-20s for boys. Given that the adolescent brain is still developing, and given the role of sleep in brain ‘plasticity’ or development, there is some concern that long-term sleep restriction, like that seen in typical teens, may have enduring impacts on the brain.  

 

Put your phone away early in the night.  If you are going to look at a device at night, get a blue light filter! Don’t drink caffeine too late in the day. Try to go to bed and wake up at the same time every day (even on weekends).  Take sleep seriously!

 

In addition to all of the negative consequences of sleep loss on brain health (which is my area of expertise), sleep is also necessary for optimal function of other body systems. Medical conditions, such as obesity, diabetes, and cardiovascular disease are all linked to sleep loss.  In fact, you may have heard that not getting enough sleep can make you fat.  One reason is because sleep is essential to keep the endocrine system functioning optimally.  When sleep is restricted, you produce higher levels of ghrelin, a hormone that triggers hunger and reduces energy expenditure (makes you hungry and lazy). Cortisol, a stress hormone, is also dysregulated by sleep loss, as is blood glucose, both of which further contribute to increased hunger. On top of that, as I mentioned above, impulse control is reduced under conditions of sleep loss, so you are more likely to give in to temptation and make poor food choices. 

 

There are a million other things to say about how important sleep is, but I will end by saying that if you don’t get enough sleep you’ll get fat and won’t reach your academic potential! ☺