On the topic of sleep...

SLEEP is non-negotiable. Though socially, we tend to kick it aside, and often joke about how little sleep we get, how tired we are, and that there’s plenty of time to sleep when we’re dead. The fact remains, that sleep is one of the most powerful modulators of health.  This is most elegantly demonstrated by the very simple fact that every organism on Earth with a developed nervous system, participates in some form of sleep.  Research suggests that we spend about one third of our lifetime sleeping.  I love prescribing sleep to my patients because of the quick buy-in:  it’s free, it is easy, everyone loves how it makes them feel, and as Shakespeare said, it is “the main course in life’s feast, and the most nourishing.”  

HOW sleep nourishes our body continues to fascinate me, and the more I learn about it, the more I recognize the true depth of what sleep expert Matthew Walker PhD meant when he said that sleep is “mother nature’s best effort to counter death.”  The body’s innate intelligence naturally evokes the desire to sleep whenever it is put under stress of any kind - when it falls to illness, after a tremendous physical exertion, during intense emotional stress, or while suffering from grief or depression.  Under all of these circumstances, and many more, sleep rejuvenates our health through a variety of different mechanisms.  

WHILE food plans, and exercise prescriptions all require a some level of active patient engagement and participation, sleep is the exact opposite.  Sleep is not something we do to our body.  Instead, we have to create the proper environment for sleep to be ushered in.  In other words, we have to give ourselves permission for sleep to occur.        

THERE are two factors that determine when our body wants to sleep, and when it wants to be awake.  The first is your circadian rhythm - a living twenty-four hour clock that helps us to determine sleep and wakefulness.  Regulated by the suprachiasmatic nucleus (SCN) in the hypothalamus,  it controls body temperature, hunger and thirst, mood and emotion, metabolic rate, and even the amount of urine that is produced.  This rhythm is primarily signaled through light and dark phases of our environment, and melatonin plays a role in this.  Melatonin is a hormone that regulates the time that sleep occurs, and it is turned on by darkness.  Once receptors in our eyes begin to perceive an absence of natural light, rising levels of melatonin hormone begins to be secreted from our pineal gland - telling the body “settle down now, it's time to sleep.”  The role of melatonin in our body is currently being studied and has been shown to produce a tremendous number of benefits to the body including hormone synthesis, body temperature regulation, immune system regulation, metabolic support, cognitive support, and pro-aging, but for now we will focus our discussion of it based on its chronobiotic mechanisms

PEOPLE vary widely in their  rhythmic patterns, and it has been established that there are three general chronotypes which are strongly genetically determined.  The “morning larks” make up about 40% of the population, and happily wake up around dawn, falling asleep early in the evening, despite their best efforts.  The “night owls” make up about 30% of the population, have a strong distaste for early morning hours, and often seek out professions with hours that run later into the evening.  The remaining 30% of the population lean somewhere in the middle of the two, with a slight preference for evening wakefulness.  It is important to recognize that there is a broad undercurrent of social negativity in labeling night owls as “lazy,” as our society has strongly biased the workforce to favor the circadian rhythms of morning larks.  This has led to chronic sleep deprivation in this group type. It has been demonstrated that higher rates of illnesses such as diabetes, cancer, and heart disease are prevalent in night owl chronotypes, as well as higher rates of depression and anxiety.  This is unfortunate of course because the evolution of these two major chronotypes were adapted to ensure the survival of our ancestral tribal clans.  Our primal ancestors would have been vulnerable to attack if the entire tribe were to sleep simultaneously, therefore early watch and late watch occurred in shifts to ensure the safekeeping of all.  One could argue that the night owl’s social standing did a “full one-eighty”, as they were likely once provided with more gratitude and respect amongst tribal communities for the protection they provided their clans in ancient times.  

THE second factor that determines our body’s sleep and wake patterns is known as sleep pressure.  A chemical byproduct of cellular metabolism known as adenosine is the responsible driver of this pressure.  The more we utilize cellular energy, the more adenosine we create.  A buildup of adenosine in the brain creates a demand or desire for sleep.  Levels increase in the brain over the period of time that we are awake.  The longer one remains awake, the more of this chemical accumulates in the brain and makes you feel sleepy.  Adenosine usually reaches its maximum capacity for tolerance after we have been awake for between twelve to sixteen hours, at which point, your body will feel a strong urge to sleep.  The desire, or urge to sleep is the body’s way of communicating with us - its operator - to find a quiet place to rest and sleep for a while.  While we should succumb to this urge, most of us do the exact opposite, and power through.  There are, of course, things that can positively or negatively influence the level of adenosine that builds in the brain, and exercise is one of them.  Because exercise drives cellular metabolism, through its energy demand, it also drives the  build up of adenosine in the brain.  This positive sleep pressure, will provide the body with the urge to sleep, and can therefore promote healthy sleep and wake patterns.  

CAFFEINE on the other hand, can actually block adenosine receptors, in effect, masking or muting the adenosine’s impact on sleep pressure in the brain.  While the effects of caffeine peak in the body around thirty minutes after consumption, its half-life is approximately five to seven hours.  This means that if you have a cup of coffee around 8:00 am, six hours later at 2 pm, around 50% of that caffeine will still be active and circulating around your body, blocking adenosine receptors.  It will take another six hours - until 8:00 pm - for the liver to fully process and remove the caffeine, relinquishing its seat on the adenosine receptor, and clearing space for adenosine to take its rightful place on its receptor to give your body sleepy signals.  For those who consume more than one cup of coffee, energy drink, tea, chocolate, soda, or even pain relievers, per day, this cycle repeats and compounds on itself, amplifying the half-life of caffeine and altering brain chemistry to disrupt your sleep wake cycle.  

THE urge to sleep once your liver has completed its detoxification and removal of the caffeine molecules can be intense for some, as the adenosine which had been prevented from attaching to its rightful receptors, continues to accumulate in the brain as time wake time passes.  Once the receptors become available, the oversupply of adenosine rush longingly into their receptors as quickly as children rush toward an empty seat when the music stops in music chairs.  This produces the well known, and largely disliked sensation known by many as a “caffeine crash,” and its symptoms can be quite unpleasant, ranging from difficulty concentrating, and jitteriness, to feeling severely depleted, slow moving, and fatigued.  

ONCE you finally do fall asleep, adenosine must be purged from the brain in order to reset the sleep pressure barometer and rhythm.  Required for this occurrence, is about eight hours of healthy, continual sleep.  A newly discovered and fascinating “cleaning crew” brain detoxification system known as the glymphatic system participates in the removal of adenosine, along with other cellular debris from the brain, ultimately resetting the brain and preparing it for another twelve to sixteen hours of wakefulness.    

AS we have mentioned above, sleep is not something we can actively do to our body, but rather a condition that we must create in order to allow our body permission to sleep.  To facilitate sleep conditions, there are several things we can do, or not do, to help ensure our sleep is healthy, and optimized.  The most important thing one can do when attempting to optimize sleep is to set a sleep schedule, and to stick to it - even on the weekend.  Much like the sleep schedule one sets for a toddler, consistency is the key to success.  Perhaps more important than setting the bedtime, is setting a wake up time.  The wake up time is the key to syncing your circadian rhythm - which is the master regulator of your wake sleep cycle.  Every morning when you wake up, make efforts to expose yourself to morning sunshine within thirty minutes of waking - even if it is overcast.  This will help to modulate cortisol production, and support your stress reactions all day.  Limit heavy food consumption late in the evening.  You want to give your body enough time to finish digesting your last meal at least three hours before you hit the sack.  Though, for those with blood sugar dysregulation, a small snack before may be useful to ensure a full night's sleep.  Limit fluid intake, around one hour before bedtime to prevent excessive wake up for bladder emptying.  Limit alcohol and caffeine use for eight hours prior to bedtime.  Although it is widely believed that alcohol calms the nervous system, it has a rebound wakeup effect as your liver attempts to detox it out of the body overnight.  Alcohol can also impair breathing overnight, leading to wakeup.   Limit or discontinue the use of all electronics around two hours before bedtime.  If unavoidable, block blue light on devices or wear blue light blocking glasses.  Light exercise before bed, or body-led stretching is a great way to cue your body to relax. Lower the lights in your home after the day’s daily activities have ended.  Many of us continue to brightly illuminate multiple rooms in the house in the evening time, simply out of habit.  But if light is not directly needed in one or more rooms, consider dimming the lights, or turning off overhead lights in favor of lower lumens lamps.  Candles, or a fireplace can support mental relaxation, and even ignite a bit of romance in the evening.   

REGARDING the space you sleep in, there is much we can do to support sleep.  Make sure your bedroom is dark, electronics-free, and cool.  Lower the temperature in your sleeping room to around 65 (18.3℃).  Our body temperature drops as a cue for sleep, and therefore taking a hot bath or shower can help you feel sleepy as your body temperature drops after getting out.  If you wake up frequently, or have trouble falling asleep, remove the clock from your room.  If you do not fall asleep within twenty minutes, do not lay in bed!  Get out of bed, and do a relaxing activity outside of your bedroom until you feel sleepy.  Prioritize your bed, sheets and blankets.  We spend one third of our lives in bed, so splurge on a supportive mattress and bedding that is made of natural materials to ensure breathability.    

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