How Sleep Apnoea Causes Fatigue
Obstructive sleep apnoea (OSA) is the most commonly undiagnosed sleep disorder and one of the most significant preventable causes of daytime fatigue. It affects an estimated 1 billion people globally and the majority are undiagnosed.
What sleep apnoea does to your sleep
In OSA, the upper airway repeatedly collapses during sleep, causing breathing to pause for 10–90 seconds at a time — sometimes hundreds of times per night. Each pause triggers a brief arousal as the brain registers the oxygen drop, preventing sustained deep or REM sleep. The person usually has no memory of these arousals but wakes unrefreshed and exhausted.
Even mild sleep apnoea (5–14 events per hour) significantly impairs sleep quality and daytime functioning. Moderate to severe apnoea (15–30+ events per hour) produces severe daytime sleepiness, impaired reaction time (comparable to significant alcohol intoxication), and dramatically increased accident risk.
Who has sleep apnoea
Risk factors include: male sex, obesity (particularly central adiposity), age over 40, large neck circumference, retrognathia (recessed jaw), nasal congestion, and alcohol use. However, OSA is significantly underdiagnosed in women — who often present differently (more insomnia, fatigue, and mood symptoms rather than obvious snoring and witnessed apnoeas) and are less likely to be referred for sleep studies.
Snoring and observed breathing pauses are the classic signs, but many people with OSA are unaware of these. Morning headache, waking with a dry mouth or sore throat, persistent fatigue despite adequate sleep time, and nocturia (night-time urination) are also common presentations.
Diagnosis and treatment
Diagnosis is by polysomnography (in-lab sleep study) or home sleep apnoea testing. The primary treatment is CPAP (continuous positive airway pressure), which is highly effective — most CPAP users report dramatic improvements in daytime energy within the first few nights of use.
Alternatives include mandibular advancement devices (oral appliances that advance the jaw to keep the airway open), positional therapy for position-dependent OSA, and in some cases surgical intervention.
Our assessment asks about key sleep apnoea symptoms and flags it as a likely contributor to your fatigue when present.
Frequently Asked Questions
What are the common symptoms of sleep apnoea?
Common symptoms of sleep apnoea include loud snoring, observed breathing pauses during sleep, morning headaches, dry mouth or sore throat upon waking, persistent fatigue despite adequate sleep, and nocturia.
How does sleep apnoea lead to daytime fatigue?
Sleep apnoea causes repeated interruptions in breathing during sleep, leading to frequent awakenings that prevent deep and restorative sleep, resulting in significant daytime fatigue.
Who is most at risk for developing sleep apnoea?
Individuals at higher risk for sleep apnoea include those who are male, obese, over 40 years old, have a large neck circumference, or experience nasal congestion, although it is often underdiagnosed in women.
What treatments are available for sleep apnoea?
The primary treatment for sleep apnoea is CPAP therapy, which is very effective, but alternatives include oral appliances, positional therapy, and in some cases, surgery.