Catathrenia
Catathrenia is the medical term for groaning during sleep. Persons with this condition emit long, sometimes loud groans on exhalation or out-breathing, most commonly during REM or deep sleep. Researchers increasingly categorize catathrenia as a sleep-related breathing disorder, akin to sleep apnea. Catathrenia doesn’t appear to correlate with any known health risk, nor does it reflect a disturbed emotional state or physical discomfort during sleep.

Circadian Rhythm Sleep Disorder
The circadian rhythm is the body’s internal clock. It’s a cycle that lasts 24 hours and keeps biological processes in sync. Your Circadian rhythm also plays a role in when you sleep. A circadian rhythm sleep disorder occurs when this internal clock is not functioning properly.

Insomnia
Insomnia is characterized by the inability to sleep in three ways; falling asleep, staying asleep or waking too early. Many people will experience insomnia at some point in their lives as there are many causes and these can sometimes be temporary.

Jet Lag
Jet lag is a sleep disorder caused by rapid travel across time zones. Humans have an internal clock, or circadian rhythm, which serves to regulate many of the body’s biological functions, including the sleep-wake cycle. This natural synchronization between body and day is thrown off by fast travel over great distances to the east or west.  

Kleine-Levin Syndrome (KLS)
Kleine-Levin syndrome, or KLS, is a rare disorder associated with extreme fatigue and excessive sleepiness, causing patients to sleep as much as 20 hours a day. Other characteristics include bouts of intense hunger and strong sexual desire. Symptoms are intermittent, coming and going in phases for months or years at a time. 

Narcolepsy
Narcolepsy is a disease of the central nervous system that causes excessive uncontrollable daytime sleepiness. It is due to the deficiency of a protein called hypocretin (hi-poe-kree-tin), which is important in controlling the timing, expression and occurrence of normal sleep. When hypocretin is deficient, components of rapid-eye movement sleep will suddenly occur during waking hours. 

Night Terrors
Night terrors are short-lived states of agitation and extreme fear experienced while asleep. Episodes are marked by screaming, sweating, flailing, and bolting upright in bed. Night terrors are most common in children. Though unpleasant, night terrors rarely pose a threat to health. An exception would be a recurrent condition, which results in sleep deprivation and may signal a more serious underlying medical issue. 

Periodic Limb Movement Disorder
Periodic Limb Movement Disorder (PLMD) are repetitive limb movements, usually in the lower extremities (legs), that occur during sleep and can sometimes interrupt sleep. Some people are not aware that they are having these limb movements as they can happen in light sleep phases.

RBD
REM sleep behavior disorder, or RBD, is a type of sleep disorder known as parasomnia.  In these conditions, unusual or dangerous events occur that disrupt sleep. In RBD, these events take place during the REM phase of sleep, which is the deep dream state of sleep. For most people, REM sleep involves a temporary paralysis of the body’s muscles. But for people with RBD, that temporary paralysis never takes place, causing them to act out their vivid REM dreams physically—including punching, kicking, shouting, and grabbing—that interrupts their sleep.

Restless Legs Syndrome

Restless legs syndrome (RLS) is a disorder in which a person experiences an uncontrollable urge to move the legs especially in the evening and prior to sleep. RLS typically worsens over time. 

Sleep Apnea
Sleep apnea is a condition where momentary lapses in breathing occur due to the throat relaxing too much during sleep and blocking the airway. Those who have sleep apnea may not be aware they have the disorder as they usually feel like they slept through the night. Common symptoms are snoring (not everyone who snores has sleep apnea) or choking or waking gasping for air.

There are three primary forms of sleep apnea:

• Obstructive sleep apnea: The most common form of the sleep apnea results from the relaxation of the throat muscles, leading to air flow blockage. 
• Central sleep apnea: Central sleep apnea occurs when the brain fails to properly regulate respiratory muscle movement, causing the body to “forget” to breathe during sleep.
• Complex sleep apnea syndrome: This form of sleep apnea is a combination of the other two.

Sleep Talking
Formally called somniloquy, sleep talking is considered harmless and does not typically require medical attention. If you are prone to talking in your sleep, you may speak in single words, full sentences, or gibberish. You will likely be unaware you’re sleep talking unless someone else points it out to you.

Sleepwalking
Sleepwalking is exactly what it sounds like: walking in one’s sleep. Sleepwalking can encompass other behaviors as well, including sitting up, talking, doing household chores and, in extreme cases, going outside or driving a car, all while in a state of unconsciousness. Sleepwalking is most common in children, generally harmless, and usually outgrown. It can, however, signal some underlying medical condition and represent a potential safety danger.

Snoring
Snoring is the loud, rasping sound that accompanies breathing in sleep. It’s a common medical condition, affecting an estimated 90 million Americans. Though usually considered a nuisance rather than a problem, snoring can be evidence of a more serious underlying medical issue, such as obstructive sleep apnea.

Shift Work Sleep Disorder
Shift work sleep disorder (SWSD) is a chronic medical condition affecting persons who work nontraditional hours, typically second or third shift. Working evening or nighttime hours can disrupt the body’s natural sleep-wake cycle, leading to abbreviated rest intervals and an overall loss of sleep. Persons with SWSD commonly experience insomnia, grogginess, extreme sleepiness, poor concentration, and mood swings. 

Insufficient Sleep Syndrome
Insufficient sleep syndrome is the lack of sleep that occurs when people become too busy to spend enough time at rest. Sufferers from this form of sleep deprivation are not always aware of what’s happening; it’s a condition that comes on gradually as one takes on new commitments to family, work, or friends. Because insufficient sleep syndrome shares many of the same symptoms as other types of sleep disorders, it can be difficult to diagnose.