Sleep Disorders Overview: Insomnia, Sleep Apnea, Restless Legs & When to Seek Help

An estimated 50 to 70 million Americans suffer from chronic sleep disorders, according to the National Institutes of Health. Poor sleep is not just an inconvenience — it is a clinical condition with measurable consequences for cardiovascular health, cognitive function, and quality of life. Understanding the most prevalent sleep disorders is the first step toward effective treatment.

Insomnia: The Most Common Sleep Complaint

Insomnia is characterized by difficulty falling asleep, staying asleep, or waking too early and being unable to return to sleep, despite having adequate opportunity to rest. The American Academy of Sleep Medicine (AASM) distinguishes between two forms:

Acute insomnia lasts a few days to a few weeks and is often triggered by stress, travel, or a life event. It typically resolves on its own once the precipitating factor passes.
Chronic insomnia occurs at least three nights per week for three months or longer. It affects roughly 10 percent of adults and is associated with increased risk for depression, anxiety, and cardiovascular disease.

Treatment: CBT-I as the Gold Standard

The National Institute of Neurological Disorders and Stroke (NINDS) and the AASM both recommend Cognitive Behavioral Therapy for Insomnia (CBT-I) as the first-line treatment for chronic insomnia, ahead of pharmacological options. CBT-I is a structured program that addresses the thoughts, behaviors, and habits that perpetuate sleep difficulties. A meta-analysis published in the Annals of Internal Medicine (Mitchell et al., 2012, PubMed) found that CBT-I produces durable improvements in sleep onset latency and total sleep time, with effects that persist well beyond the end of treatment — something sleep medications cannot reliably claim.

Obstructive Sleep Apnea: A Hidden Epidemic

Obstructive Sleep Apnea (OSA) occurs when the muscles in the back of the throat relax excessively during sleep, causing repeated airway blockages. Each episode can last 10 seconds or longer and may occur dozens or even hundreds of times per night. The Mayo Clinic identifies loud snoring, gasping during sleep, and excessive daytime sleepiness as hallmark symptoms.

OSA is strikingly common. Research from the American Journal of Epidemiology estimates that moderate to severe sleep-disordered breathing affects approximately 10 percent of men aged 30 to 49 and 17 percent of men aged 50 to 70. Many cases remain undiagnosed because patients are unaware of their nighttime breathing disruptions.

Treatment: CPAP and Beyond

Continuous Positive Airway Pressure (CPAP) therapy remains the most effective and widely prescribed treatment for moderate to severe OSA. The device delivers a steady stream of pressurized air through a mask, keeping the airway open throughout the night. The Stanford Sleep Medicine Center notes that CPAP adherence significantly reduces daytime sleepiness, lowers blood pressure, and decreases cardiovascular risk. For milder cases, oral appliances that reposition the jaw, positional therapy, and weight loss may also be effective.

Restless Legs Syndrome

Restless Legs Syndrome (RLS) is a neurological condition that produces an overwhelming urge to move the legs, usually accompanied by uncomfortable sensations described as crawling, tingling, or aching. Symptoms typically worsen during periods of rest and in the evening, making it difficult to fall asleep. The NINDS reports that RLS affects up to 7 to 10 percent of the U.S. population, with women affected more frequently than men.

RLS has a strong genetic component, and it is also associated with iron deficiency, kidney disease, and peripheral neuropathy. Treatment may involve iron supplementation when levels are low, dopaminergic medications, or alpha-2-delta ligands such as gabapentin enacarbil, which the AASM clinical practice guidelines recommend for moderate to severe cases.

Narcolepsy

Narcolepsy is a chronic neurological disorder in which the brain loses its ability to regulate the sleep-wake cycle normally. The NINDS describes two types:

Type 1 narcolepsy involves excessive daytime sleepiness along with cataplexy — sudden, brief episodes of muscle weakness triggered by strong emotions. This form is caused by the loss of neurons that produce the neuropeptide hypocretin (also called orexin).
Type 2 narcolepsy involves excessive daytime sleepiness without cataplexy.

Narcolepsy affects roughly 1 in 2,000 people, and symptoms often begin in adolescence or young adulthood. Diagnosis typically requires an overnight sleep study (polysomnography) followed by a Multiple Sleep Latency Test (MSLT). Treatment includes scheduled naps, stimulant medications, and sodium oxybate for cataplexy.

Parasomnias: Unusual Behaviors During Sleep

Parasomnias are a category of sleep disorders that involve abnormal movements, behaviors, emotions, or perceptions during sleep. The Mayo Clinic lists common examples:

Sleepwalking (somnambulism) — walking or performing complex behaviors while in deep sleep.
Night terrors — episodes of intense fear, screaming, and agitation during non-REM sleep, most common in children.
REM Sleep Behavior Disorder (RBD) — physically acting out vivid dreams during REM sleep, which can result in injury. RBD is notable because research published in Neurology (Postuma et al., 2009, PubMed) has shown it may be an early marker for neurodegenerative diseases such as Parkinson’s disease.

Parasomnias are typically diagnosed through a detailed sleep history and polysomnography. Treatment depends on the specific disorder and severity but may include safety measures, medication, or treatment of underlying conditions.

When to See a Doctor

The AASM recommends consulting a healthcare provider if you experience any of the following:

Persistent difficulty falling or staying asleep lasting more than a few weeks
Loud, chronic snoring, especially with witnessed pauses in breathing
Excessive daytime sleepiness that interferes with work, driving, or daily activities
Uncomfortable sensations in the legs that disrupt your ability to rest
Unusual behaviors during sleep, such as walking, talking, or acting out dreams

Understanding the Sleep Study

A polysomnography (PSG), commonly known as a sleep study, is the diagnostic gold standard for many sleep disorders. Conducted overnight in a sleep laboratory, it simultaneously records brain waves (EEG), eye movements (EOG), muscle activity (EMG), heart rhythm (ECG), breathing patterns, blood oxygen levels, and body position. The Stanford Sleep Medicine Center explains that this comprehensive data allows sleep specialists to identify the type and severity of a disorder with high precision.

Home sleep apnea tests (HSAT) are also available for patients with a high pretest probability of moderate to severe OSA. These portable devices are less comprehensive than in-lab PSG but offer a more convenient and cost-effective screening option.

Key Takeaways

Insomnia is the most common sleep disorder; CBT-I is the recommended first-line treatment, not medication.
Obstructive Sleep Apnea is highly prevalent and frequently undiagnosed; CPAP therapy remains the most effective treatment for moderate to severe cases.
Restless Legs Syndrome affects up to 10 percent of the population and may be linked to iron deficiency — a treatable cause.
Narcolepsy is a neurological disorder that requires clinical testing (PSG and MSLT) for accurate diagnosis.
Parasomnias such as sleepwalking and REM Sleep Behavior Disorder warrant medical evaluation, especially when they pose a safety risk.
If sleep difficulties persist for more than a few weeks or impair daytime functioning, consult a healthcare provider — effective treatments exist for nearly all sleep disorders.
A sleep study is a painless, non-invasive diagnostic tool that provides detailed information about what happens during your sleep.