Health professionals usually recommend that as adults, we should eat anywhere from five-to-13 helpings of fruits and vegetables per day, drink at least two litres of water and exercise daily to maintain a high quality of life. The other part of that equation is sleep. While we’re told that seven-to-nine hours of sleep is what we need to function, what we really need is long periods of uninterrupted sleep every night. Those suffering from sleep disorders such as obstructed sleep apnea (OSA) and snoring normally experience fragmented sleep episodes due to their airway being intermittently blocked when the throat muscles relax. This interrupted breathing can occur during the different stages of sleep, which can have a detrimental effect on health.
Understanding the Different Stages of Sleep
If you have ever watched a child sleep, you have likely seen the various sleep stages that we all go through. According to the second edition of Neuroscience (various editors) on the National Centre for Biotechnology Information database, “humans descend into sleep in stages that succeed each other over the first hour or so after retiring.”
The first four sleep stages are considered non-rapid eye movement (NREM) sleep, while the other stage, REM sleep, is said to account for approximately 18–22 per cent of our total sleep time. The stages are as follows:
1. The drowsy period, which is the lightest period of non-REM sleep and can be easily disrupted.
2. Light sleep, where your heart rate and brain waves continue to slow preparing you for deep sleep.
3. Moderate to deep sleep, the beginning of deep sleep, characterized by the lack of muscle movement or eye activity.
4. Slow-wave sleep (SWS), the deepest phase of NREM sleep, where breathing and heart rate slows allowing your body to repair itself.
5. REM sleep, also known as dream sleep, is where the brain becomes more active, blood pressure increases and breathing becomes faster.
What Happens When NREM and REM Sleep is Disrupted
It is said that a healthy sleeper should cycle through the various sleep stages every 90 or so minutes during an eight-hour sleep period. However, sleep disorders caused by upper airway obstruction such as OSA can occur in both NREM sleep as well as during REM sleep. In the article, Obstructive Sleep Apnea During REM Sleep: Clinical Relevance and Therapeutic Implications, it’s said that there is an increased tendency for upper airway collapse during REM sleep due to the decreased muscle tone of the genioglossus (one of the muscles in the mouth associated with the tongue). While it is difficult to awaken someone in NREM deep sleep (sleepwalking has been known to occur during this stage), if someone is woken up during deep sleep, it can cause “dissociation characterized by complex motor activity with limited judgment and awareness,” says Dr. John Cline, PhD, in the Psychology Today article, The Mysterious Benefits of Deep Sleep.
Lack of Sleep and Your Health
A chronic lack of sleep, or poor quality sleep, can increase your risk of high blood pressure and heart disease, weight gain and the build-up of dangerous plaques in your body. Studies have also indicated that REM OSA is independently associated with prevalent and incident hypertension, non-dipping of nocturnal blood pressure, increased insulin resistance, and impairment of human spatial navigational memory. In the Psych Central article on how Sleep Apnea Affects REM Sleep and Memory, studies have found that lack of sleep during REM sleep can impair spatial memory in humans even when other sleep stages are intact. Spatial memories act as our internal compass and help us from getting lost or remembering where our car keys are located.
How CPAP Therapy Can Help
While it’s been shown that continuous positive airway pressure, or CPAP, is a proven method to decrease the health risks associated with sleep apnea, new studies have shown that it may even help improve sleep quality during the various stages of sleep. In a case report conducted by the Institute of Biomedicine and Molecular Immunology, it was observed in patients with OSA who used a CPAP Mask that the amounts of slow wave and REM sleep achieved during the first night of CPAP application exceeded those usually observed in normal subjects.
Read more about the benefits of sleep from our Snore MD sleep specialists and see how we are there to help you get the best quality sleep possible with effective sleep apnea and snoring solutions tailored to your needs. Contact us to find a sleep apnea clinic near you.
About the author:
Kristin Froneman has more than 25 years as a writer, reporter and photographer. Her work has appeared in national publications, including Maclean’s.
Kristin helps readers to digest up-to-date obstructed sleep apnea news through researching and integrating trusted medical studies and their findings.