What Are Sleep Disorders?

Sleep disorders, also sometimes called sleep-wake disorders, are characterized by problems with the quality, timing, and amount of sleep, which can cause stress and reduced functioning. Sleep disorders can be associated with both physical and mental health problems, and can also worsen pre-existing conditions.
The International Classification of Sleep Disorders (ICSD) includes seven major categories of sleep disorders:
- Insomnia
- The most common type of sleep disorder that involves problems falling asleep or staying asleep despite adequate opportunity to do so
- There are three types of insomnia
- Short-term insomnia disorder
- Chronic insomnia disorder
- Other insomnia disorder (symptoms that do not meet criteria for the other two types of insomnia)
- Sleep-related breathing disorders
- Characterized by abnormal breathing during sleep
- Snoring may be normal or abnormal
- There are four main groups
- Central sleep apnea syndromes
- Obstructive sleep apnea (OSA) disorders
- Sleep-related hypoventilation disorders
- Sleep-related hypoxemia disorder
- Central disorders of hypersomnolence
- Characterized by a primary complaint of daytime sleepiness that is not due to another sleep disorder
- Narcolepsy is a type of hypersomnolence sleep disorder
- Circadian rhythm sleep-wake disorders
- Characterized by a chronic or recurrent sleep disturbance due to changes in the patient’s circadian system or misalignment between the environment and an individual's sleep-wake cycle
- Some types of circadian rhythm disorders include
- Shift work disorder and jet lag disorder: the most common types of circadian rhythm sleep disturbances
- Sleep-wake phase disorders
- Non-24-hour sleep-wake rhythm disorder: common in blind patients
- Parasomnias
- Undesirable physical events (movements or behaviors) or experiences (emotions, perceptions, dreams) that occur during sleep
- Non-rapid eye movement (NREM)-related parasomnias include confusional arousals, sleepwalking, sleep terrors, and sleep-related eating disorder
- REM-related parasomnias include sleep paralysis and nightmare disorder
- Other parasomnias are not associated with a particular state of sleep and include: exploding head syndrome, sleep-related hallucinations, sleep enuresis (bedwetting), parasomnia associated with medical disorders, parasomnia due to a medication or substance, and unspecified parasomnia
- Sleep-related movement disorders
- Characterized by movements that disturb sleep
- Patients may or may not be aware of these movements
- Some types of sleep-related movement disorders include:
- Restless legs syndrome
- Periodic limb movement disorder
- Sleep-related cramps
- Sleep-related bruxism (teeth grinding)
- Other sleep disorders
- These types of sleep disorders do not fit into any of the other categories, such as disorders related to environmental disturbances
What Are Symptoms of Sleep Disorders?
Symptoms of sleep disorders depend on the specific disorder.
Symptoms of insomnia include:
- Difficulty falling asleep or staying asleep
- Variable sleep
- Daytime fatigue or sleepiness
- Forgetfulness
- Inability to concentrate
- Irritability
- Anxiety
- Depression
- Decreased motivation or energy
- Increased errors or accidents
- Persistent worry about sleep
Symptoms of sleep-related breathing disorders include:
- Morning headache
- Loud snoring
- Fatigue
- Daytime sleepiness
- Restless sleep
- Awakening with choking, gasping, or smothering
- Dry mouth or sore throat
- Frequently waking to urinate
- Awakening unrested, groggy
- Low energy
- Difficulty concentrating
- Memory problems
- Dry mouth or sore throat
Symptoms of central disorders of hypersomnolence include:
- Excessive daytime sleepiness (EDS)
- Sudden muscle weakness (cataplexy)
- Transitioning from being awake to being asleep (hypnagogic hallucinations)
- Sleep paralysis
- Frequent short naps during the day
- Difficulty sleeping at night
- Night-time compulsive behaviors such as eating and nocturnal smoking
- Obesity
Symptoms of circadian rhythm sleep-wake disorders include:
- Extreme daytime sleepiness
- Insomnia (see above)
- Tiredness
- Decreased alertness
- Problems with memory and decision-making
- Headache
Symptoms of parasomnias include:
- Sleepwalking
- Act in a way that is strange and confused on waking up
- Night terrors
- Acting out vivid dreams in your sleep: may be violent and can cause injury to the patient
- Nightmare disorder
- Sleep paralysis
- Sleep talking
- Bedwetting (enuresis)
- Groaning
- Hearing a loud imaginary noise just before falling asleep or awakening
- Binge eating and drinking in the night with minimal or no memory of the binge
Symptoms of sleep-related movement disorders include:
What Causes Sleep Disorders?
The causes of the various sleep disorders vary.
Causes of insomnia include:
- Changes in sleeping environment (temperature, light, noise)
- Stress: loss of a loved one, loss of a pet, divorce, or job loss
- Recent illness, surgery, or pain
- Use of or withdrawal from stimulants (caffeine), some medications, illegal drugs, or alcohol
- Jet lag
- Shift work
- Mental health problems, such as depression, anxiety, and posttraumatic stress disorder
- Illnesses, especially those that cause pain, stress, or difficulty breathing
- Neurological disorders, such as Parkinson disease and Alzheimer disease
- Other sleep disorders
- Irregular sleep habits
- Genetics
- May not have a known cause
Causes of and risk factors for sleep-related breathing disorders include:
- Increasing age: more common in middle and older age adults
- Male sex: two times more common in men than in women
- Obesity
- Sedation from medication or alcohol
- Airway abnormality
Causes of and triggers for central disorders of hypersomnolence include:
- Unknown in some cases
- Genetics
- Hormonal changes, such as during puberty or menopause
- Significant psychological stressors
- Sudden changes in sleep patterns
- Infection, such as swine flu or a streptococcal infection
- Autoimmune disorder
- Head injury
- Brain tumor
- Multiple sclerosis (MS)
- Encephalitis
Causes of circadian rhythm sleep-wake disorders include:
- External factors
- Sleep habits
- Work schedule
- Travel
- Internal factors
- Age
- Genetics
- Underlying medical condition
Causes of and risk factors for parasomnias include:
- Age: some problems are worse in childhood such as sleepwalking or bedwetting
- Genetics
- Stress
- Post-traumatic stress disorder (PTSD)
- Certain medications
- Drug or alcohol abuse
- Other disorders, such as sleep apnea, congestive heart failure, and Parkinson’s disease.
Causes of sleep-related movement disorders include:
How Are Sleep Disorders Diagnosed?
Sleep disorders are diagnosed with a patient history and physical exam. Tests or procedures that may be used to diagnose sleep disorders or to rule out other underlying conditions include:
- Daily sleep log
- Sleep study (polysomnography)
- Record of activity and movement with a monitor or motion detector, generally worn on the wrist throughout the day and night (actigraphy)
- Home sleep apnea testing
- Home devices that monitor breathing, oxygen saturation, position, and heart rate
- Melatonin sampling
- Core body temperature measurements
- Hormone tests
- Electrocardiogram (“ECG”)
- Computerized tomography (CT) scan
- Pulmonary function tests
- Magnetic resonance imaging (MRI) of the brain
What Is the Treatment for Sleep Disorders?
Treatment for insomnia includes:
- Cognitive behavioral therapy for insomnia (CBT-I)
- Sleep education
- Sleep restriction or sleep compression
- Stimulus control
- Sleep hygiene
- Relaxation exercises
- Sleep medications, both over-the-counter (OTC) and prescription
Treatment for sleep-related breathing disorders includes:
- Continuous positive airway pressure (CPAP)
- Adjusting sleep position (to stay off the back)
- Weight loss
- Avoiding alcohol and other sedatives
- Dental devices
- Surgery
Treatment for central disorders of hypersomnolence includes:
- Behavior changes
- Medications
- Stimulants
- Medications to treat cataplexy
- Histamine H3 antagonists/inverse agonists
Treatment for circadian rhythm sleep-wake disorders includes:
- Light therapy
- Light restriction (dark therapy)
- Chronotherapy
- Sleep deprivation/phase advance
- Medicines to help you fall asleep or to help you stay awake
- Healthy lifestyle changes including steps to improve your sleep habits
Treatment for parasomnias includes:
- Education to avoid triggers
- Creation of safe environment
- Discontinue medications that may be causing the problem such as serotonergic antidepressants for rapid eye movement (REM) sleep behavior disorder (RBD) or short-acting hypnotics for complex sleep-related behaviors
- Do not stop taking a prescribed medication without first talking to your doctor
- Medications
Treatment for sleep-related movement disorders includes:
- Behavioral Changes
- Exercise
- Stress reduction techniques
- Don’t smoke
- Reduce or avoid caffeine and alcohol consumption
- Massage legs or soak in a hot bath
- Medications
- Parkinson's disease medications
- Sleeping pills
- Certain anti-seizure medications
- Narcotic pain medications
- Iron treatment
From 
https://www.uptodate.com/contents/classification-of-sleep-disorders
https://www.uptodate.com/contents/insomnia-beyond-the-basics
https://www.uptodate.com/contents/insomnia-treatments-beyond-the-basics
https://www.uptodate.com/contents/sleep-apnea-in-adults-beyond-the-basics
https://www.uptodate.com/contents/narcolepsy-the-basics
https://www.nhlbi.nih.gov/health-topics/circadian-rhythm-disorders
http://www.sleepallies.org/circadian_rhythm_sleep-wake_di.php
http://sleepeducation.org/essentials-in-sleep