Sleep Apnea | Why Do You Keep Waking Up Tired?

Sleep apnea is a clinical sleep disorder characterized by repeated interruptions of breathing during sleep. These pauses, known as apneas, can last from a few seconds to minutes and may occur 30 times or more an hour. The most prevalent form is Obstructive Sleep Apnea (OSA), which happens when the muscles in the back of the throat relax and fail to keep the airway open, leading to a physical blockage. A less common type is Central Sleep Apnea (CSA), where the brain fails to send the proper signals to the muscles that control breathing. This distinction is critical: OSA is a mechanical problem, while CSA is a neurological one. During an apneic event, the oxygen level in the blood drops. The brain senses this inability to breathe and briefly rouses the person from sleep to reopen the airway. This can happen so quickly that the individual has no memory of it, but it severely fragments the sleep cycle and prevents the deep, restorative sleep necessary for proper brain and body function.

While loud, chronic snoring is a primary indicator of sleep apnea, it is not the only symptom. Many individuals experience abrupt awakenings accompanied by gasping or choking sensations. Due to the poor quality of sleep, excessive daytime sleepiness, known as hypersomnia, is a major complaint. This can lead to difficulty with concentration, memory lapses, and a noticeable decline in cognitive performance. Other common symptoms include waking up with a dry mouth or a sore throat, morning headaches resulting from decreased oxygen levels during the night, and mood changes such as irritability or depression. It is essential to recognize these symptoms as part of a larger clinical picture, as they signal that the body is not receiving the restorative benefits of a full night's sleep.

Untreated sleep apnea poses significant risks to neurological health. The recurrent episodes of oxygen deprivation, or hypoxia, can damage brain cells and impair the function of neurotransmitter systems. This has a direct impact on cognitive functions, particularly memory consolidation, attention, and executive functions like decision-making and problem-solving. Furthermore, the constant sleep fragmentation prevents the brain from cycling through the necessary sleep stages, especially deep and REM sleep, which are vital for neural repair and memory processing. Over time, this chronic stress on the brain can increase the risk for more severe neurological conditions, including stroke and cognitive decline.

The effects of sleep apnea extend throughout the body, with a particularly strong impact on the cardiovascular system. The sudden drops in blood oxygen levels that occur during apneic episodes place immense strain on the heart and blood vessels, leading to an increase in blood pressure. Consequently, untreated sleep apnea is a major risk factor for hypertension, heart attacks, cardiac arrhythmias (such as atrial fibrillation), and stroke. Beyond cardiovascular issues, sleep apnea is also closely linked with metabolic problems. It can disrupt the regulation of hormones like insulin, increasing the risk of developing type 2 diabetes and contributing to weight gain, which in turn can worsen the apnea itself.

The definitive diagnosis of sleep apnea is made through a sleep study, technically called a polysomnography (PSG). This test records brain waves (EEG), eye movements, muscle activity, heart rhythm (ECG), breathing patterns, and blood oxygen levels during sleep. A PSG is typically conducted overnight in a specialized sleep laboratory where a technician can monitor the readings in real-time. Alternatively, for some patients suspected of having moderate to severe OSA, a Home Sleep Apnea Test (HSAT) may be prescribed. This is a simplified version of the PSG that the patient can use in their own home. The data from either test allows a physician to determine the presence and severity of sleep apnea by calculating the number of apneas and hypopneas (episodes of shallow breathing) per hour of sleep, a value known as the Apnea-Hypopnea Index (AHI).