Sleep Disorders Beyond Insomnia [2026]: The Conditions Most People Don't Know They Have

Insomnia — difficulty falling or staying asleep — receives the majority of sleep disorder attention and treatment. Several other sleep disorders are more prevalent, more physically harmful, and more frequently undiagnosed: obstructive sleep apnea affects an estimated 26% of adults aged 30-70, the majority undiagnosed. Restless legs syndrome affects 5-10% of adults. Circadian rhythm disorders are the hidden cause of many sleep and mood complaints attributed to stress or "just being a night owl." Here is the honest guide to the sleep disorders that don't get enough attention.

Sleep Apnea: The Most Underdiagnosed Serious Condition

Obstructive sleep apnea (OSA) — repeated partial or complete obstruction of the upper airway during sleep, causing breathing pauses that trigger arousals — affects an estimated 1 billion people globally per a 2019 Lancet Respiratory Medicine estimate, with the majority undiagnosed. The consequences of untreated OSA extend far beyond poor sleep: OSA is independently associated with hypertension (the repeated hypoxia and arousal cycles drive sustained blood pressure elevation), cardiovascular disease, type 2 diabetes, cognitive impairment, and depression — making it one of the highest-impact undiagnosed health conditions.

The symptoms that should prompt OSA evaluation: snoring (the most common reported symptom, though not all snorers have OSA), witnessed apneas (bed partners observing breathing pauses are the most specific indicator), morning headaches (from overnight CO2 retention), excessive daytime sleepiness despite adequate time in bed, and waking unrefreshed consistently. The Epworth Sleepiness Scale (a standardized questionnaire) provides a structured assessment — scores above 10 suggest pathological sleepiness warranting evaluation. Home sleep apnea testing is now widely available and significantly more accessible than in-lab polysomnography for initial diagnosis.

Restless Legs Syndrome

Restless legs syndrome (RLS) — an urge to move the legs accompanied by uncomfortable sensations (described as crawling, creeping, pulling, or aching) that worsen at rest and improve with movement, occurring primarily in the evening and night — is both common (5-10% prevalence) and frequently misattributed to anxiety, circulation problems, or "just being uncomfortable." The diagnostic criteria require all four features: urge to move legs, worsened at rest, relieved by movement, and worse in the evening/night. Secondary causes (iron deficiency is the most common — ferritin below 75 ng/mL should prompt supplementation before other treatment) should be ruled out before pharmacological treatment.

Honest Bottom Line: Obstructive sleep apnea affects an estimated 26% of adults 30-70, the majority undiagnosed, with consequences including hypertension, cardiovascular disease, diabetes, and cognitive impairment — far beyond poor sleep. Prompt OSA evaluation for: snoring with witnessed apneas, morning headaches, unrefreshed waking, or Epworth Sleepiness Scale score above 10. Home sleep testing has made OSA diagnosis significantly more accessible. RLS (urge to move legs at rest, evening/night predominance, relieved by movement) affects 5-10% and is frequently misattributed — check ferritin level first, as iron deficiency is the most common secondary cause.