Have you thought of what it would be like living in the mountains year-round? Medical professionals find it is important to look at what living at high elevations can do to the human body. One activity heavily affected is sleep. As mentioned in previous blog posts, visitors often have trouble falling asleep, staying asleep, and feeling rested in the morning. A recent study published in Physiological Reports measured the effects of sleeping patterns at high elevation. The participants experienced a simulated elevation inside a hyperbaric chamber. This mimicked sleeping at elevations of 3000 meters (9,842 feet) and 4050 meters (13,287 ft) for one night and then sleeping at sea level for several nights to establish a baseline for the research participants. Participants exercised for 3 hours in the hyperbaric chamber allowing researchers to observe how the lower oxygen concentrations affected their ability to perform strenuous tasks. The group that slept in a simulated 4050 meter environment had an increased heart rate that was 28% higher and an oxygen saturation 15% lower than the 3000 meter participants. When comparing sleep itself, the group at 4050 meters had 50% more awakening events throughout each night. This goes along with previous research on this blog that states that people who sleep at high altitude complain of insomnia and frequent awakening when first arriving at high elevation.
These numbers increase even more dramatically when compared to participants at sea level. Related symptoms reported during this study showed the incidence of acute mountain sickness occurred in 10% of the participants at a simulated 3000 meters, increasing to 90% at 4050 meters. As mentioned, the average heart rate increases and oxygen saturation decreases as the elevation increases. The baseline heart rate at sea level was 62 beats per minute, increasing to 80 at 3000 meters and 93 at 4050 meters. Ideally health care providers aim to oxygenate vital organs by keeping the oxygen saturation level between 92-100%. The lower the oxygen level the harder it is to keep organs properly profused. Age, health status, and place of residence are taken into consideration when examining study reports. Oxygen saturation at sea level was 98% decreasing to 92% at 3000 meters and 84% at 4050 meters.
As mentioned in a previous post by Dr. Neale Lange, sleeping at high altitudes can be hard due to the frequent awakenings and nocturnal hypoxia caused by the low oxygen levels at higher elevation. This study reiterates these findings with the results of the average oxygen saturation at 3000 meters being around 92%. Dr. Lange also found that sleep apnea was often more prominent and had more negative effects on the human body in environments that were lower in oxygen. This study agrees with that statement finding that people with sleep apnea had twice the hourly awakenings compared to those at higher elevation that did not have sleep apnea. Dr. Lange also pointed out that the contribution of hypobaric atmosphere to symptoms at altitude as opposed to pure hypoxemia is unknown. Frisco, Colorado is at an elevation of 2800 meters. Ongoing research at Ebert Family Clinic including residents and visitors along with laboratory studies such as this one can guide decisions about interventions and treatment to improve sleep and help us enjoy our time in the mountains.
Figueiredo PS, Sils IV, Staab JE, Fulco CS, Muza SR, Beidleman BA. Acute mountain sickness and sleep disturbances differentially influence cognition and mood during rapid ascent to 3000 and 4050 m. Physiological Reports. 2022;10(3). doi:10.14814/phy2.15175
Blog post: HOW DO YOU DEFINE A GOOD NIGHT’S SLEEP?:AN INTRODUCTION TO THE SLEEPIMAGE RING, AN INTERVIEW WITH DR. NEALE LANGE
Casey Weibel is a 2nd year student at Drexel University, born and raised in Pittsburgh, Pennsylvania. He went to Gannon University for his undergrad and got a degree in biology. Before PA school, Casey was an EMT. He enjoys hiking and kayaking and is a big sports fan.
Dr. Neale Lange is a leader in sleep medicine who started his medical training in South Africa and now practices Pulmonary and Sleep Medicine for UCHealth in Denver.
Sleep plays a crucial role in cognitive behavior and physical well-being but is often times taken for granted. As Dr. Neale Lange puts it, many people have been taught or trained to devalue sleep in an effort to maximize the time awake to study, get caught up on work, or complete other tasks1. However, research over the years has demonstrated that the toll sleep deprivation plays on the body is significant. Sleep deprivation can lead to impairment in memory, cognition, and emotion, and can lead to chronic medical conditions such as diabetes, heart disease and cancer2. It is also thought that sleep deprivation and hypoxemia are associated with white matter disease in the brain and deep slow wave sleep, is what fixes it4.
Furthermore, Dr. Lange states that sleeping at altitude carries its own risks. Sleeping at altitude, where there is less oxygen in the air, can cause overall poor sleep quality, increased awakenings, frequent arousals, marked nocturnal hypoxia and periodic breathing.. Additionally, sleeping at altitude can negatively impact our sleep architecture, increasing the amount of light sleep and decreasing the amount of deep slow-wave and REM sleep which plays a key role in memory creation, retention and emotional control and personal behavior3.
In hopes to defining a person’s sleep at altitude, Dr. Lange started a sleep lab in Summit County at St. Anthony Summit Hospital, which, as he put it, “opened a can of worms” when he saw how sick and complicated patients sleep apnea cases were. Time and time again, he saw that when patients who were struggling with sleep apnea were given 2L of supplemental oxygen by nasal cannula, the apnea improved. Additionally, those patients with sleep apnea who descended around 4,000 ft to Denver have improved saturations but may still have sleep apnea. His facility study included baseline tests at two hours without oxygen and then two hours with oxygen while a person slept. He found that although the apnea improved in many, improvements in sleep itself did not always follow.
This left him with the question of: How do we measure “good sleep?” Well, as he states, it is not that simple. Though the obvious answer may be to turn to medications to determine good sleep, this can be misleading. Medications have an amnestic effect on people because when they wake up in the morning, if their memory is blank, they feel that they have had a good night’s rest. But in reality, this is subjective. The true data collected during sleep is objective, so to answer his question of measuring sleep, he turns to a tool of cardiopulmonary coupling (CPC). This tool, called a SleepImage Ring, looks similar to an Apple Watch and is worn around a patient’s finger throughout the night. Using Bluetooth technology, data is collected and transferred through a smartphone for analysis, providing the patient with a vast amount of data about their sleep.
The SleepImage System is the only FDA approved medical grade technology with the simplicity of a consumer device on the market for use in both children and adults. It is intended for use by a healthcare professional to establish a patient’s sleep quality and aid in evaluation and clinical diagnosis of sleep disorders and sleep disordered breathing, or SDB. It uses CPC technology which is “based on calculations and spectral analysis of cardiovascular- and respiratory data” collected during sleep using continuous “normal sinus rhythm ECG- or PLETH (Plethysmogram from a PPG sensor) signal as the only input requirement.” The output metrics from the SleepImage System include “sleep duration (SD), total sleep time (TST), wake after sleep onset (WASO) and sleep quality (SQI) and sleep disordered breathing (SDB) related output metrics that include an Oxygen Desaturation Index (ODI), an Apnea Hypopnea Index (sAHI), a Respiratory Disturbance Index (sRDI), Central Sleep Apnea Index and the Sleep Apnea Indicator (SAI) that is derived from Cyclic Variation in Heart Rate (CVHR)6. With a PLETH signal including saturations, the SDB data conforms with the American Academy of Sleep Medicine AHI scoring and severity definitions.” Additionally, we can determine how long a patient spends in various sleep stages, including stable, unstable and REM sleep, determine apnea events, and autonomic nervous system activity. The data is generated and presented on the SleepImage Quality Report (shown below). The ring and report are designed as such where you can do individualized, precise sleep medicine. It is true when Dr. Lange says “the devil is in the details” referring to the vast amount of information that can be analyzed from this device during one night of sleep.
Currently, the gold standard to monitoring and diagnosing sleep disorders is polysomnography, also known as a sleep study, which records certain body functions as you sleep to determine brain activity, oxygen, heart rate, breathing, as well as eye and leg movements5. It can detect types of sleep apnea; however, this comprehensive test is typically done during an overnight stay in a hospital or other sleep center, which presents a disadvantage. The disadvantage to polysomnography is that it takes people out of their natural sleeping environment, is costly, and time consuming, which deter a large portion of people from partaking in sleep studies.
Dr. Neale Lange explains that this device can change the way we look at our sleep and may provide better insight into a person’s sleep on a greater scale due to the ease of wearing the device over multiple nights, compared to spending one night in a sleep lab for a study. A study done on 65,000 users indicated that there is added benefit to multi-night testing as compared to single night testing. Testing for sleep apnea on only one night has been shown to vary from night to night, indicating that single night testing potentially misclassifies 20% of people7. This device provides the ease of multi-night testing for patients, which is a significant advantage and increases accurate diagnosis of sleep disordered breathing. To Dr. Lange, “it is about individualized patient care” and evaluating “the person sitting in front of [him]” which makes this device so valuable. Dr. Lange states that, “living at altitude is a particular challenge, and if people are thinking ahead,” instead of wondering, “how long do I want to live at altitude,” a better question would be, “how can I invest in brain wellness.”
In summary, sleep deprivation, especially at altitude, is an important focus that people should not overlook. At Ebert Family Clinic in Frisco, one of the most important questions asked is, “how did you (or your child) sleep last night?” Now, with the SleepImage Ring, we can objectively evaluate our patient’s sleep which can aid in the diagnosis and management of various conditions.
South African Dental Association. (2021, November 25). The sleep disorder spectrum: Mouth breathing to Osa – Dr Neale Lange (WEB126). YouTube. Retrieved December 5, 2021, from https://www.youtube.com/watch?v=agZruGNfFNI
Irish, L. A., Kline, C. E., Gunn, H. E., Buysse, D. J., & Hall, M. H. (2015). The role of sleep hygiene in promoting public health: A review of empirical evidence. Sleep medicine reviews, 22, 23–36. https://doi.org/10.1016/j.smrv.2014.10.001
Voldsbekk, I., Groote, I., Zak, N., Roelfs, D., Geier, O., Due-Tønnessen, P., Løkken, L. L., Strømstad, M., Blakstvedt, T. Y., Kuiper, Y. S., Elvsåshagen, T., Westlye, L. T., Bjørnerud, A., & Maximov, I. I. (2021). Sleep and sleep deprivation differentially alter white matter microstructure: A mixed model design utilizing advanced diffusion modelling. NeuroImage, 226, 117540. https://doi.org/10.1016/j.neuroimage.2020.117540
Lechat, B., Naik, G., Reynolds, A., Aishah, A., Scott, H., Loffler, K. A., Vakulin, A., Escourrou, P., McEvoy, R. D., Adams, R. J., Catcheside, P. G., & Eckert, D. J. (2021). Multi-night Prevalence, Variability, and Diagnostic Misclassification of Obstructive Sleep Apnea. American journal of respiratory and critical care medicine, 10.1164/rccm.202107-1761OC. Advance online publication. https://doi.org/10.1164/rccm.202107-1761OC
Catherine Atkinson is a second-year Physician Assistant student at Red Rocks Community College in Arvada, CO. She was born and raised in Colorado where she has lived her entire life. She received her undergraduate degree in integrative physiology from The University of Colorado- Boulder. Prior to PA school, she was an ophthalmic technician at Colorado Retina Associates. In her free time, she loves cooking, skiing, playing golf and spending time with her family and friends.