Perhaps I should have started with these issues as they are more straight-forward, but I am roughly going in order of what is most common (although, by no means creating a comprehensive list). As you will see, understanding how hormones, stress and circadian rhythms work (see Part 1 if you missed it) will help you understand just how serious the #1 obesity-related sleep problem is!
Obesity, then Apnea, and then Poor Sleep
Snoring is a Sign
Ok, though snoring is not a medical diagnosis AND you do not need to be obese to be a snorer, we need to recognize it for the signal it should be for us that there is a potentially serious health problem happening! Snoring is simply the sound of turbulent airflow through the airways. A deviated septum, large tongue, small lower jaw, low palate, or enlarged adenoids/tonsils can cause snoring, but regardless of cause, think of the sound as heralding the need to get evaluated (and that includes children). Additionally, as we age the muscle tone of the tongue and throat can get too relaxed and medications or alcohol can worsen this.
Obesity is a major cause of snoring
Snoring in obesity is due to the weight of a large stomach and/or chest reducing lung volumes and a large neck adding weight to airways. Less obvious is the unseen accumulation of fat at the base of the tongue and along our airways on the inside. Eventually, when the obstruction get to the point of complete collapse of the airway you cannot move air at all and you stop breathing; this is called apnea (without breath), or hypoapnea (less breath) if partial obstruction occurs. Sleep studies analyze these breathing events and summarize them as the apnea-hypoapnea index (AHI).
So I take fewer breaths at night. So what?
Not breathing at night is clearly disruptive to your sleep, and sleep apnea has been correlated with a higher risk of heart failure, hypertension, diabetes, strokes, and sudden death. In children it affects growth and development. But why?? When you stop breathing in the middle of the night, oxygen levels to your brain quickly decline. There are few stress triggers for the brain greater than asphyxiation! Thus, huge amounts of cortisol are dumped into your system to cause the sympathetic nervous system to kick in a stress response which sets off a cascade of several reactions (reflexes) in the body. (Now would be a good time to go back and read Part 1 if you haven’t already)
Long live Cortisol, King of the Hormones
Cortisol arouses your sleepy brain to an awakened state to gasp a breath. However, many times you do not remember waking as you may only need to be brought to a semi-conscious level of brain activity for your body to respond with deeper/stronger breaths (contractions of diaphragm) to overcome the obstruction or tighten oral muscle tone. Thus, throughout the night cortisol is helping you stay just conscious enough to stay alive, and at the same time never allowing your body deep or REM sleep. Without these deeper sleep stages you will not be able to process memories as well or get the full rest your body needs. This leaves you with the classic symptoms of excessive daytime sleepiness accompanied by concentration, memory, and mood problems.
The increase in cortisol also disrupts your circadian rhythms, setting off the multitude of dysfunctional hormone signals we discussed last week. This sets you up for blood sugar problems and more weight gain (which needless to say, but I will anyway, worsens your obstructive sleep apnea).
Finally, the cascade of sympathetic actions mediated by the nervous system also includes an increased heartbeat and vasoconstriction (tightening) of blood vessels, raising blood pressure to get more blood to the brain (another way of increasing available oxygen). This results in higher resting blood pressure and heart rate as if you were working out all night (i.e. another reason to be tired all day and eventually maybe even have heart failure or a stroke).
This is not very common, but enough of an issue that I felt it was worth mentioning. Obesity has been linked to an increased risk of developing restless leg syndrome (RLS). RLS is characterized by a discomfort in the legs (usually only in the evenings) that creates an irrepressible urge to move them to relieve the feeling. Unfortunately, the relief is very transient, leaving sufferers constantly moving through the night, disrupting their sleep (and those who sleep near to them). The connection is not fully understood, but has been suggested to be related to dopamine levels in the brain. An interesting observation is that eating early in the night can lessen symptoms of RLS.
Sleep-related eating disorder – SRED
Wake up and discover an unexpectedly messy kitchen and/or missing food and are confounded by the inability to lose weight? You may have SRED. With this condition, one not only sleepwalks but also involuntarily eats while they are asleep, waking the next morning unaware of the event. One study attempting to determine the prevalence of this disorder found that as much as 4.6% of college students described symptoms consistent with this disorder (I don’t think being intoxicated should count so I question this statistic seriously!) So, unless you also have another mental disorder and admit to eating coffee grounds and kitty litter (unusual and non-food items are often consumed), I’m probably not going to buy your story…but you can see if it will get you off the hook with your spouse! ?
Sleep is important! And we need to stop minimizing the serious effects of ignoring our body’s innate need for adequate sleep whether we are obese or not (yet). So, if you are considering turning over a new leaf in the new year, consider turning IN sooner as one of those goals. And as a final encouragement, remember that for any goal it doesn’t have to be perfect to be helpful or worthwhile. A 6-year study of both men and women done in Italy found that for every additional hour of sleep routinely obtained, the incidence of obesity decreased 30%.