Most of the time when we talk about the limits of CPAP, we focus on how the very poor compliance rates (perhaps as low as 20%) reduce its efficacy. Now a new study shows that even “compliance” as commonly defined is inadequate because it doesn’t help with most interruptions of REM sleep, which occur later in the night, when people have stopped using CPAP.
REM vs. NREM Sleep Apnea
Researchers attempting to explore the metabolic impact of sleep apnea wondered whether it made a difference whether sleep apnea disturbances occurred during rapid eye movement (REM) sleep or during non-REM (NREM) sleep. It turns out that sleep disturbance during REM sleep is more harmful than disturbance during NREM sleep.
Researchers discovered this by looking at the impact of REM and NREM sleep disturbances on the level of hemoglobin A1C, also called glycated hemoglobin, in sleep apnea sufferers with diabetes. Measuring hemoglobin A1C is a common test for how effective a person’s blood sugar control has been over time (up to the last four months or so).
The measurements showed that sleep disturbance during REM sleep was independently correlated with elevated hemoglobin A1C. It didn’t matter whether you had more or less overall, the number of REM sleep interruptions you experienced made a difference in the effectiveness of your diabetes control.
Why CPAP May Not Be Effective
CPAP compliance is typically defined as spending four hours using your CPAP machine a night. After that, many people remove the mask because of discomfort, often unconsciously. However, because REM sleep tends to dominate the second half of sleep, many people aren’t getting the benefit of CPAP during crucial REM sleep.
Researchers estimate that a four hour protocol for compliance only covers about 40% of REM sleep, while a seven hour protocol would cover about 85% of REM sleep.
The Importance of REM Sleep
Although this study was focused on the metabolic effects of REM sleep, specifically diabetes control, REM sleep has many other important functions, such as:
If a sleep apnea treatment isn’t working to preserve REM sleep, we have to wonder whether it can be considered to be working at all.
There Is an Alternative
Fortunately, CPAP is not the only treatment available for sleep apnea. For some people, oral appliance therapy may give better results. And because it doesn’t feel as uncomfortable, you’re less likely to throw it off during the night, which may lead to longer treatment, although this hasn’t been formally studied.
To learn whether oral appliance therapy might be better for you, please contact the Advanced Dental Sleep Treatment Center in Omaha today.