What is sleep apnea, and why is it important?

A couple of weeks ago, I spent a night at the sleep lab at Dartmouth Hitchcock in Lebanon doing a sleep study for sleep apnea. When I arrived, I was assigned a private room with an ensuite. After changing into my PJs, I started the long process of being hooked up to sensors. It took the nurse about an hour to connect sensors to my body. Sensors in my legs checked for restless legs syndrome. Sensors on my chin measured muscle tone in the throat. Sensors around my rib cage measured my breathing. I had sensors on my mouth and nose that measured air intake and temperature. And sensors peppered the scalp to measure brain waves. A camera followed eye movement to record the different stages of sleep. To my surprise, I was able to sleep even while connected to all the wires that measured my sleep cycles and breathing. About 15-30% of American males and 10-15% of American women struggle with sleep apnea. It is more common among African Americans and among people beyond middle age. Many of the people with sleep apnea go undiagnosed and untreated, which reduces their quality of life and lifespan. If you don't feel rejuvenated when you wake up in the morning, you might be one of them. What is sleep apnea? Sleep apnea occurs when throat muscles relax during sleep, blocking airways. Blockage can reduce or stop airflow, causing hypoxia (none) or hypopnea (partial). Apnea is defined as the absence of airflow through the airway for at least 10 seconds. Hypopnea is defined as a reduction of airflow of at least 50% accompanied by a decrease in oxygen level by at least 3% for at least 10 seconds. This airway disruption causes gasping and fragmented sleep cycles. You may believe you slept well, but deep sleep was disrupted. The common sleep apnea profile is an overweight man over 60. Clinicians often miss cases in people outside this group, especially slim women. If a client reports waking up tired in the morning or experiences excessive daytime sleepiness or fatigue, I screen them for sleep apnea regardless of whether they fit the typical profile. This ensures that individuals who may not appear to be at risk still receive appropriate evaluation. Some questions to ask yourself: Do you wake with a dry mouth? This may mean mouth breathing, which raises apnea risk. Do you wake up with a morning headache? Hypoxia and hypopnea can cause headaches by reducing oxygen to the brain. Does your partner tell you that you snore or gasp when you sleep? Snoring is associated with apnea. Do you wake up more than once to urinate during the night? When you are engaged in passive activities during the day, such as driving in the passenger seat, reading a book, or watching a movie, will you fall asleep? If any of these questions resonate with you, I recommend discussing a referral to a sleep study with your primary care provider. Sleep apnea and inflammation Sleep apnea leads to chronic systemic inflammation. The glymphatic system is your brain's cleaning crew. It is responsible for clearing waste and large protein molecules from the brain and functions optimally during slow wave sleep phases. Intermittent hypoxia from sleep apnea disrupts sleep cycles and the glymphatic system's ability to perform its essential housekeeping tasks. Clean brain is crucial for preventing neurodegenerative diseases. Proteins like beta-amyloid and tau, which are implicated in Alzheimer's disease and other forms of dementia, are accumulated in the brain when the glymphatic system is not functioning appropriately. Sleep apnea and your heart Nitric oxide is a signaling molecule that protects the integrity of your blood vessels and reduces inflammation and blood pressure. When an apnea occurs, oxygen saturation drops; once the body gasps, the airway opens and oxygen floods back in. This happens repeatedly, sometimes hundreds of times per night. Reperfusion after hypoxia triggers a burst of reactive oxygen species, increasing oxidative stress, leading to inflammation in blood vessels, and reducing nitric oxide production. The result is an increase in plaque formation in arteries, atherosclerosis, and high blood pressure; all the risk factors for a heart attack. Stress response When you are in deep sleep, your body shifts from sympathetic response (fight or flight), which is characterized by alertness, to parasympathetic response (rest, relax, digest). A parasympathetic response is characterized by a lower heart rate and blood pressure, deeper breathing, and relaxed muscles. Sleep apnea keeps the brain in a state of constant hypervigilance, as it must closely monitor oxygen levels. The heart doesn't get the opportunity to reduce rate and contractility; it works in full force, putting you at higher risk for adverse cardiovascular outcomes. Increased sympathetic response during the night can "leak" to the day, leading to stress, depression, and anxiety. Metabolic health During sleep, the body reboots its metabolic function; growth hormones are secreted, the liver stores glucose, and the cells increase their sensitivity to insulin. Each apnea episode shifts the autonomic nervous system into a fight or flight response, leading to a spike in cortisol. When cortisol spikes, muscles and the liver release glucose from storage to the blood, preparing the body for a threat that never occurs. One of the hallmarks of sleep apnea is elevated fasting glucose in the morning. Chronic high cortisol reduces insulin sensitivity, leading to insulin resistance, contributes to fat deposition around the abdomen, and increases muscle loss. All signs and symptoms of metabolic conditions or prediabetes. Sleep apnea care plan If you suspect sleep apnea, do not ignore it; speak with your PCP about getting a referral for a sleep study. The nearest sleep lab is located at Dartmouth Hitchcock in Lebanon. Based on my experience, in-home sleep study results are frequently inconclusive, often necessitating a more comprehensive in-hospital sleep study that requires an overnight stay. Though the in-home study may seem convenient, it may require two tests rather than one. The gold standard of care for sleep apnea is Positive Airway Pressure Devices (CPAP machine). However, some lifestyle changes can reduce the occurrence of sleep apnea. For reducing sleep apnea: Reduce weight if you are overweight. Sleep on your side. Avoid alcohol because it acts as a muscle relaxant. Quit smoking. Increase muscle tone by engaging in exercise. Sleep is a cornerstone of well-being. Many of my clients struggle to fall or stay asleep; others sleep through the night but wake up groggy and tired. I refer them to a sleep study because I know that whatever the reason was that brought them to me, they will not get better if they don't sleep well.