Obstructive Sleep Apnea | Why Do I Still Feel Tired After a Full Night's Sleep?

Obstructive Sleep Apnea is a clinical disorder characterized by the repetitive collapse of the upper airway during sleep. This physical obstruction prevents air from reaching the lungs, leading to a pause in breathing known as an "apnea." A less severe event, where the airway is only partially blocked, is called a "hypopnea." During these events, the oxygen saturation in the blood (SpO2) decreases. The brain detects this drop in oxygen, a state called hypoxia, and perceives it as a life-threatening situation. In response, it triggers a brief arousal from sleep—often so short the person doesn't remember it—to reactivate the throat muscles and reopen the airway, usually resulting in a gasp or snort. This cycle can repeat hundreds of times per night. Crucially, these constant arousals prevent the brain from entering or sustaining the deep, restorative stages of sleep, such as N3 (slow-wave sleep) and REM sleep. Without adequate time in these stages, the brain and body cannot perform essential recovery functions, leading to significant daytime sleepiness, cognitive impairment, and other long-term health consequences, regardless of how many hours were spent in bed.

Several factors increase the likelihood of developing Obstructive Sleep Apnea. The most significant is excess body weight, particularly fat deposits around the neck, which can physically narrow the airway. However, OSA is not exclusive to individuals who are overweight. A person's natural anatomy plays a critical role; factors such as a large tongue, enlarged tonsils or adenoids, a small or recessed jaw (retrognathia), or a high-arched hard palate can predispose an individual to airway collapse. Gender and age are also key factors. Men are diagnosed with OSA more frequently than women, though the risk for women increases substantially after menopause due to hormonal changes that affect muscle tone. As people age, the natural loss of muscle tone in the throat muscles also contributes to an increased risk. Finally, lifestyle choices can exacerbate the condition. The consumption of alcohol or sedative medications relaxes the muscles in the throat, making airway collapse more likely during sleep.

The definitive diagnosis of OSA is made through a sleep study. The gold standard is an in-laboratory polysomnography (PSG). During a PSG, multiple physiological parameters are monitored overnight, including brain wave activity (EEG), eye movements (EOG), muscle activity (EMG), heart rhythm (ECG), breathing effort, airflow, and blood oxygen levels. The data collected allows clinicians to determine the frequency and severity of breathing interruptions. The key diagnostic metric is the Apnea-Hypopnea Index (AHI), which represents the average number of apnea and hypopnea events per hour of sleep. An AHI of 5-15 is classified as mild, 15-30 as moderate, and over 30 as severe OSA. For some patients, a Home Sleep Apnea Test (HSAT) may be used as a more convenient, though less comprehensive, diagnostic alternative.

Untreated OSA poses significant risks to long-term health. The recurrent episodes of hypoxia and the stress response from frequent awakenings place considerable strain on the cardiovascular system. This leads to a substantially increased risk for developing hypertension (high blood pressure), coronary artery disease, heart attack, and stroke. The condition is also strongly linked to metabolic dysfunction, including insulin resistance and an increased risk of developing Type 2 diabetes. Cognitively, the chronic sleep fragmentation impairs attention, concentration, and memory. Furthermore, there is a strong association between OSA and mood disorders, with untreated individuals reporting higher rates of depression and anxiety.

The primary and most effective treatment for moderate to severe OSA is Continuous Positive Airway Pressure (CPAP) therapy. A CPAP device delivers a constant stream of pressurized air through a mask worn during sleep. This pressure acts as a pneumatic splint, preventing the soft tissues of the throat from collapsing and ensuring the airway remains open. While highly effective, patient adherence can be a challenge. For individuals with mild to moderate OSA, or for those who cannot tolerate CPAP, an oral appliance may be an alternative. These custom-fitted devices, known as Mandibular Advancement Devices (MADs), work by repositioning the lower jaw and tongue forward to increase the space in the airway. Lifestyle modifications are also fundamental to managing OSA. This includes weight loss, which can significantly reduce or even eliminate apnea events in some individuals, avoiding alcohol and sedatives before sleep, and positional therapy (e.g., sleeping on one's side instead of the back). In specific anatomical cases, surgical interventions may be considered.