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What sleep does for your body

With mounting demands on our time, for either personal or professional reasons, and a capped number of hours in the day, our modern lives have come to privilege wakefulness, leaving less time for sleep. Each day we take in a huge amount of information, some of which may be new to us. Sleep is a vital part of our 24-hour day, when our body repairs and recharges from all of this activity to prepare for the day ahead. 


Believe it or not, sleep is actually a very active, rich, and nuanced phenomenon. During sleep, our body and brain move in and out of several stages, each marked by a different pattern of brain and bodily activity. For instance, during deep sleep our body dips to its lowest core body temperature. During deep sleep, which constitutes about 15-20% of the typical night, we also see our blood pressure dip to its lowest point in the day. Why is this stage so important? The dipping of body temperature and heart rate allow for vital repair of tissues and organs. For this reason, short sleepers are at significantly greater risk for high blood pressure and cardiovascular disease.


Another vital stage of sleep is Rapid Eye Movement or REM sleep, which constitutes about 20-25% of your average night. REM sleep is where most of our dreaming takes place, but we also see learnings from our day solidify at this stage and transfer to longer term storage. In sum, sleep is food for our brain and our body.


In recent years, research has also uncovered something fascinating about sleep and the brain. We have evidence to show that clearance of toxins in the brain happens at an accelerated rate when we sleep, compared to when we’re awake. At night, fluid called cerebral spinal fluid rushes through the brain at a greater rate than when we are awake. This fluid washes through the brain then, on its way out, takes away dangerous toxins that simply accumulate after wakefulness, receiving and processing information, and the normal wear and tear from our day. The removal of these toxins is absolutely critical, for without this, they can accumulate and may increase your risk for long-term concerns, such as neurocognitive decline and Alzheimer’s disease. 


We also all know, all too well, the behavioral consequences of short sleep. We have physiological evidence to show this as well. Short sleepers have more activity in the “fight or flight” region of the brain than healthy sleepers. Therefore, after a short night of sleep it is more likely that you have a “shorter fuse,” or are more likely to lash out at loved ones. Short sleepers also have more depressed mood, are a bit more irritable, anxious, and less able to engage in perspective taking, and likely will struggle with negative experiences or bad news. On the other hand, when we get healthy sleep, we are much more positive in mood, happier, and better able to put bad news or unfortunate events into context. We are more inclined to be understanding and compassionate to those around us.


Just like healthy nutrition and exercise, sleep is a crucial part of your day to day routine. Sleep is the time when we restore our brain and body after our day and prepare for a new day to come. It is a myth that we can cut our sleep short and ‘get by’ on short sleep (less than 7 hours at night). I challenge you to fall in love with sleep, to be passionate about making the time for this crucial process to unfold each night.