Sleep Disorders:

The Complete Guide (Apr 2024)

7 types of sleep disorders and their causes

We’ve all had nights where we struggle to sleep or days where we just can’t seem to wake up. But, for those with sleep disorders, this irregular pattern of sleeping becomes a regular occurrence.

Sleep problems in adults aren’t uncommon – it’s thought that around 50-70 million adults in the US suffer from a chronic sleep disorder.

Lack of quality sleep due to sleep disorders can have a detrimental effect on an individual’s quality of life and overall physical and mental health.

In this article, we’re going to explore the different types of sleep disorders, what causes them, and the various treatments available.

If you think you or someone close to you may have a sleep disorder, read on to learn more.

What is a sleep disorder?

A sleep disorder is a condition that affects the quality, timing, and/or amount of sleep we get. People with sleep disorders can experience an inability to function properly during the day, along with other health issues.

Sleep disorders are usually grouped into four categories:

  • Difficulty falling and staying asleep (e.g. insomnia)
  • Difficulty staying awake (e.g. narcolepsy)
  • Difficulty sticking to a regular sleep schedule (e.g. shift work disorder)
  • Unusual behaviors during sleep (e.g. parasomnias)

What causes sleep disorders?

Sleep disorders can be caused by underlying mental health or medical conditions as well as certain lifestyle factors. Some of the common causes include:

Mental health conditions

Stress, anxiety, and depression are all common causes of sleep disorders. If you’re going through a particularly stressful period, you may struggle to drift off to sleep or stay asleep. You may also experience parasomnias, such as sleepwalking or night terrors. Data shows that 75% of individuals with depression suffer from insomnia.

Medical conditions

Certain medical conditions such as chronic pain, lung disease, heart disease, and nerve disorders can cause sleep disorders in some people.

Respiratory problems

Respiratory problems can cause various sleep disorders, including sleep apnea and snoring.


Certain medications can cause the onset of some sleep disorders. For example, beta-blockers have been linked to sleep disturbances such as insomnia, nightmares, and nighttime awakenings.


Some sleep disorders, such as sleepwalking, are known to be genetic. Results from one study suggest that 62% of children with two sleepwalking parents will also sleepwalk.


Because caffeine is a stimulant, it can prevent us from getting to sleep at night. Many studies have found a link between caffeine and sleep problems, with results suggesting that consuming caffeine as much as six hours before bedtime can significantly impact sleep disturbances.


Alcohol can impact sleep quality and has also been linked to sleep disorders such as sleep apnea and insomnia.

Irregular sleep schedule

Having an irregular sleep schedule can cause individuals to suffer from certain sleep disorders. Those who work night shifts, for example, are more likely to develop ‘shift work disorder’.


Studies have shown that insomnia is more prevalent in the elderly population, leading to difficulty concentrating and mood disturbances during the day.

Symptoms of sleep disorders

While there are many symptoms of sleep disorders, and the exact symptoms you experience will depend on the sleep disorder you have, here are some of the common signs to look out for:

  • Difficulty falling asleep (regularly taking over 30 minutes to fall asleep)
  • Waking up multiple times throughout the night
  • Difficulty falling back to sleep in the night or waking early
  • Daytime sleepiness and fatigue
  • Trouble concentrating or functioning during the day
  • Needing to take naps during the day
  • Weight gain
  • Irritability
  • Depression
  • Abnormal breathing (e.g. snoring, gasping, or stopping breathing)
  • Uncomfortable sensations in limbs in the evening or when falling asleep
  • Increased movement during sleep
  • Muscle weakness during periods of strong emotion (e.g. laughing)

Types of sleep disorders

It’s thought there are over 100 different types of sleep disorders.

Here’s a list of some of the most commonly seen types, which we’ll cover in more detail below:

  • Insomnia
  • Sleep apnea
  • Narcolepsy
  • Parasomnias
  • Restless Leg Syndrome (RLS)
  • Hypersomnia (Excessive Daytime Sleepiness)
  • Sleep-wake disorders


Insomnia is a sleep disorder that affects our ability to fall or stay asleep. It’s the most common sleep disorder in the US, with around 30% of adults experiencing symptoms of insomnia. As well as nighttime sleep problems, those with this sleep disorder will experience daytime symptoms such as fatigue and inability to focus.

Insomnia can be short-term (lasting less than three months) or chronic (occurring at least three times a week and lasting for at least three months). Short-term insomnia usually happens due to stress or the sleep environment, and chronic insomnia can be caused by conditions such as depression, chronic stress, and chronic pain. Many with chronic insomnia also find their anxieties around the sleep problem can prolong the disorder.

Insomnia usually falls into the following three categories:

  • Sleep-onset insomnia: Trouble falling asleep
  • Sleep maintenance insomnia: Trouble staying asleep
  • Mixed insomnia: Symptoms of both sleep-onset and sleep maintenance insomnia

The symptoms of insomnia include:

  • Trouble falling asleep
  • Waking often in the night and having difficulty falling back to sleep
  • Waking up early in the morning
  • Feeling unrefreshed after sleep
  • Daytime problems due to lack of sleep, including fatigue, sleepiness, mood changes, irritability, and lack of concentration

Sleep apnea

Sleep apnea is a sleep-related breathing problem that arises when the airway becomes partially or fully blocked during sleep. It’s another common sleep disorder and is often seen in people who sleep on their backs or are overweight. People with sleep apnea will often snore very loudly and wake up gasping for air.

There are three different types of sleep apnea:

  • Obstructive sleep apnea (OSA): Caused by a physical blockage in the airway, usually due to the soft tissue in the back of the throat relaxing. Snoring is most common with OSA
  • Central sleep apnea (CSA): There is no physical airway blockage, but the brain fails to send signals to the muscles that control breathing, resulting in choking and gasping upon waking
  • Mixed sleep apnea: A mix of both types

The symptoms of sleep apnea include:

  • Loud snoring
  • Waking up gasping for breath or choking
  • Stopping breathing for a short period during sleep
  • Insomnia
  • Excessive daytime drowsiness
  • Mood disturbances such as irritability, depression, and anxiety
  • Morning headache
  • Dry mouth/sore throat upon waking
  • High blood pressure


Narcolepsy is a neurological disorder that blurs the line between sleep and wakefulness, meaning sleep characteristics can occur while awake. Many of the symptoms of narcolepsy are characteristics of REM sleep, which usually occurs after around 60-90 minutes in a regular sleep cycle. People with narcolepsy can fall asleep suddenly and involuntarily during day-to-day activities. Many also experience hallucinations and sudden muscle weakness (cataplexy).

There are two types of narcolepsy:

  • Type 1 (narcolepsy with cataplexy): All the symptoms of narcolepsy, as well as sudden muscle weakness (cataplexy) while awake, often triggered by strong emotions like laughing
  • Type 2 (narcolepsy without cataplexy): All the symptoms of narcolepsy, without cataplexy. Those with type 2 narcolepsy often experience less severe symptoms

The symptoms of narcolepsy include:

  • Excessive daytime sleepiness
  • Sleep attacks: falling asleep involuntarily during regular activities
  • Cataplexy: sudden muscle weakness triggered by strong emotions
  • Hallucinations
  • Sleep paralysis
  • Disrupted sleep during the night
  • Vivid dreams


Parasomnias are sleep disorders that cause unusual behavior while asleep, before sleep, or during sleep-wake transitions. Different parasomnias occur during different sleep stages.

The main types of parasomnias are:

Non-REM parasomnias: Behaviors that occur during non-REM sleep, including sleepwalking, night terrors, confusional arousals, and sexsomnia

REM parasomnias: Behaviors that occur during REM sleep, including sleep paralysis, REM sleep behavior disorder (when sleepers act out their dreams), and nightmare disorder

Other parasomnias: Behaviors that can happen in either non-REM or REM sleep and during sleep-wake transitions. These include hallucinations, bedwetting (sleep enuresis), and exploding head syndrome (hearing a loud noise in your head before falling asleep or waking up)

The symptoms of parasomnias will depend on the parasomnia you experience, but some general things to look out for include:

  • Feeling confused or disoriented upon waking
  • No memory of the event (e.g. can’t remember sleepwalking)
  • Difficulty sleeping
  • Daytime sleepiness

Restless Leg Syndrome

Restless leg syndrome (RLS), also known as Willis-Ekbom disease, is a sleep disorder that causes uncomfortable or painful sensations in the legs that can only be relieved by movement. These sensations usually occur when resting, which is why most people experience symptoms in the evening or during the night. People with RLS often find themselves getting up out of bed throughout the night to relieve the sensations, resulting in lack of sleep.

The sensations RLS sufferers experience are often described as:

  • Tingling, burning, aching, itching, or throbbing
  • Feeling as though insects are crawling inside the legs
  • A cramping sensation – particularly in the calves

The symptoms of RLS include:

  • A strong urge to move legs due to uncomfortable sensations
  • Feeling a similar sensation in the arms, chest, and face (in some sufferers)
  • Sensations can often be relieved by stretching, walking, or massaging the area
  • Symptoms get worse in the evening or at night
  • Difficulty sitting for long periods
  • Periodic limb movements in sleep (PLMS): uncontrollable jerking or twitching of legs – usually while asleep, but also when awake and resting

Hypersomnia (Excessive Daytime Sleepiness)

Hypersomnia is a condition characterized by excessive daytime sleepiness (EDS), the need for regular naps, and prolonged sleep at night. The condition is often caused by another sleep disorder, such as narcolepsy or an underlying health condition.

Hypersomnia is not the same as fatigue or feeling tired all the time.

The symptoms of hypersomnia include:

  • Needing to take regular naps during the day
  • Not feel refreshed upon waking
  • Falling asleep during the day at inappropriate times
  • Sleeping for a prolonged amount of time at night
  • Difficulty waking from a long sleep
  • Feel disoriented upon waking
  • Decreased energy
  • Anxiety
  • Irritability
  • Restlessness
  • Difficulties or slowness when thinking, speaking, or remembering things

Sleep-wake disorders

Sleep-wake disorders, also known as circadian rhythm disorders, occur when an individual’s circadian rhythm is misaligned. Our circadian rhythm regulates our sleep-wake cycle, aligning with environmental factors such as when it’s light or dark outside. People with sleep-wake disorders usually end up sleeping and feeling most awake at abnormal times, often due to their job, sleep habits, or travel, and sometimes due to internal factors.

Examples of sleep-wake disorders include:

  • Shift work disorder: Affects people who work night shifts or rotating schedules and cannot get quality sleep when the body needs it
  • Non-24-hour sleep-wake rhythm disorder: When the sleep-wake rhythm is not in sync with the 24-hour day. Common in people who are blind and who have limited light exposure
  • Jet lag disorder: Affects people who have traveled through multiple time zones in a short time period. Usually a temporary disorder that happens as a result of the sleep-wake rhythm being out of sync with the local time
  • Irregular sleep-wake rhythm disorder: Individuals experience multiple short bouts of sleep and wakefulness during a 24-hour period. For example, someone may have insomnia at night and have to take multiple naps in the day due to sleepiness
  • Delayed sleep-wake phase disorder: Individuals fall asleep later than anticipated and, as a result, struggle to wake up in the morning
  • Advanced sleep-wake phase disorder: Individuals struggle to stay awake in the early evening and wake up very early in the morning

Symptoms of circadian rhythm disorders include:

  • Difficulty falling asleep, staying asleep, or both
  • Excessive sleepiness
  • Fatigue and exhaustion
  • Difficulty concentrating
  • Trouble controlling mood and emotions
  • Aches and pains
  • Headaches
  • Stomach problems (mostly in those with jet lag disorder)
  • Symptoms interfere with daily life

Sleep disorder or lack of sleep?

While for many, fatigue can be a symptom of a sleep disorder, for others, it’s a sign of insufficient sleep. We all lead busy lives, and sleep has become more of a chore than a necessity for some. Most adults need 7-9 hours sleep a night, with some getting by on as little as six hours and others needing closer to ten. However, over a third of US adults reportedly get less than seven hours’ sleep a night. If you regularly feel tired during the day, perhaps first ask yourself whether you’re getting enough sleep at night. If you believe you are, we recommend visiting your healthcare provider.

Sleep disorder diagnosis

If you are concerned you or someone close to you may have a sleep disorder, it’s important to get it checked out. To diagnose a sleep disorder, your doctor may do the following:

  • View your medical history
  • View your sleep history (you may have to complete a sleep diary)
  • Carry out a physical examination
  • Carry out a polysomnogram or other type of sleep study to monitor your sleep patterns

Sleep disorder treatment

Once diagnosed, there are various ways to treat sleeping disorders, and the treatment you receive will depend on the type of sleep disorder you experience. Sometimes, treating your underlying health condition will also treat your sleep disorder.

Some common sleep disorder treatment options include:

  • Practicing good sleep hygiene: implementing a sleep routine, relaxing before bed, avoiding daytime naps, etc.
  • Lifestyle changes: exercising during the day, eating a healthy diet, etc.
  • Creating a comfortable sleep environment
  • Cognitive behavioral therapy (CBT) or relaxation techniques
  • CPAP (continuous positive airway pressure) machine (sleep apnea)
  • Bright light therapy
  • Medication/supplements such as sleeping pills or melatonin (usually on a short-term basis)
  • Sleep aids such as mouth guards (sleep apnea/snoring)

We hope you found our comprehensive guide to sleep disorders helpful. If you’re worried that you or someone you know may have a sleeping disorder and it’s started to affect your daily life, be sure to speak to your doctor.

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