This is a very common and frustrating experience for new Continuous Positive Airway Pressure (CPAP) users. The goal of CPAP therapy is to treat Obstructive Sleep Apnea (OSA) by delivering pressurized air to keep the airway open, which should lead to improved energy and less daytime fatigue. Feeling more tired is a paradox, signaling the therapy is not fully effective due to fragmented sleep caused by mechanical issues, physical discomfort, or other sleep disorders. Identifying the specific source of this fragmentation is the first step toward achieving restorative sleep.
Equipment Malfunctions and Setup Errors
The most immediate causes of continued fatigue relate to the device’s technical performance, which can actively disrupt sleep rather than promoting it. The single greatest threat to effective CPAP therapy is an air leak, which allows pressurized air to escape from the mask seal or the mouth. A significant leak reduces the pressure delivered to the airway, causing the residual Apnea-Hypopnea Index (AHI)—the number of breathing events per hour—to remain elevated, meaning the OSA is still under-treated.
Leaks also introduce noise and cause pressure changes as the machine attempts to compensate, which leads to frequent micro-arousals. These micro-arousals prevent deep, restorative sleep, and the resulting sleep fragmentation causes persistent daytime fatigue. Users should regularly inspect the mask cushion for wear, ensure the headgear is snug, and confirm the mask is the correct size and style for their face and sleeping position.
Another common issue is incorrect pressure settings, either too low or too high. If the pressure is too low, it fails to keep the airway fully open, resulting in gasping, snoring, and continued apneas, which mirrors the original symptoms of the sleep disorder. Conversely, pressure too high can cause discomfort, difficulty exhaling, and air leaks, all of which disrupt sleep and lead to morning grogginess. A malfunctioning motor or faulty sensor can also lead to inconsistent air pressure delivery, rendering the therapy ineffective and resulting in interrupted sleep.
Physical Side Effects of Pressurized Air
Beyond technical errors, the introduction of pressurized air itself can create physiological discomforts that fragment sleep. One frequently reported issue is aerophagia, nicknamed “CPAP belly,” which is the unintentional swallowing of air. This occurs when pressurized air enters the esophagus and stomach instead of the lungs, causing abdominal bloating, belching, and flatulence.
Aerophagia often results from either very high pressure forcing air into the digestive tract or very low pressure causing the user to gulp or gasp for air. The resulting gastrointestinal discomfort can cause the user to wake up or shift positions, leading to sleep fragmentation. Another common side effect is nasal or mouth dryness, caused by continuous airflow stripping moisture from mucous membranes. If the heated humidifier is broken, set too low, or if the user is a mouth-breather using a nasal mask, the resulting dryness can cause congestion and a sore throat, prompting awakenings.
Unmasking Underlying Sleep Conditions
If CPAP equipment is optimized and OSA symptoms are resolved, yet fatigue persists, another sleep condition may have been “unmasked.” CPAP therapy is highly effective for Obstructive Sleep Apnea, but it is not a universal cure for all sleep disorders. In some cases, the positive airway pressure can reveal or even induce a different type of breathing problem called Residual Central Sleep Apnea (RCSA).
Residual Central Sleep Apnea (RCSA)
Central apneas occur when the brain fails to send the correct signal to the breathing muscles, meaning the airway is open but no effort is made to breathe. While CPAP treats the physical obstruction, it cannot correct this neurological signaling issue. When RCSA develops or persists, the user’s AHI remains elevated due to these central events, preventing the necessary deep sleep and causing continued fatigue.
Other Unmasked Conditions
Successful treatment of OSA can sometimes reveal a previously unnoticed condition such as Chronic Insomnia, Restless Legs Syndrome, or Periodic Limb Movement Disorder. The user may become conscious of an inability to fall or stay asleep without the distraction of the major breathing issue, requiring separate diagnosis and treatment.
When to Consult Your Sleep Specialist
A brief adjustment period is normal when starting CPAP, but persistent fatigue suggests a problem requiring professional intervention. If you are consistently using your machine for at least four hours per night and your daytime sleepiness has not improved after several weeks, contact your sleep specialist. The specific data point to monitor is the residual Apnea-Hypopnea Index (AHI) displayed on your machine, which should ideally be below five events per hour.
If your machine reports an AHI consistently above this threshold, or if you notice an increase in the number of central apneas, a consultation is necessary to review your pressure settings. You should also seek professional guidance if you experience severe symptoms of aerophagia or persistent discomfort that prevents you from using the therapy. Your specialist may recommend a follow-up sleep study or a change to a different type of positive airway pressure device, such as a BiPAP or an Adaptive Servo-Ventilation (ASV) machine, especially if RCSA is suspected.