Other, less common sleep disorders include:
- REM Sleep Behavior Disorder
- Non-24-Hour Sleep Wake Disorder
- Excessive Sleepiness
Parasomnias are a group of unusual sleep behaviors that can occur before falling sleep, during sleep, or in the time between sleep and wakefulness. These are more commonly found in children, but some adults may experience them as well. These include sleepwalking, bedwetting, night terrors, and more unique ones like exploding head syndrome. Parasomnias are broken down into three categories: NREM-related parasomnias, REM-related parasomnias, and other.
REM Sleep Behavior Disorder
REM sleep behavior disorder is a condition characterized by sudden body movements and vocalizations while a person experiences vivid dreams during REM sleep. It is a specific type of parasomnia, which describes abnormal behaviors during sleep.
During normal REM sleep, the body experiences temporary muscle paralysis, known as atonia, while the brain shows activity similar to wakefulness. Blood pressure rises, breathing becomes irregular, and the eyes dart in all directions rapidly (hence, the term “rapid eye movement”). The temporary paralysis of REM sleep allows us to dream safely, lying still while the brain is active. This paralysis involves most skeletal muscles and excludes muscles that help us breathe, digest, and some muscles of the eyes. REM sleep accounts for about 25 percent of a total night’s sleep, with most of it taking place during the second half of the night.
For individuals with REM sleep behavior disorder, normal muscle paralysis does not occur, enabling the person to physically act out their dreams. REM sleep behavior disorder can manifest as small muscle twitches and quiet sleep talking to loud shouting, punching, kicking, grabbing their bed partner, and jumping out of bed. Interestingly, the dreams associated with REM sleep behavior disorder are often intense and frightening. Individuals may dream about being chased or attacked, and they can unknowingly enact the dream in real life.
Non-24-Hour Sleep Wake Disorder
Individuals with non-24-hour sleep-wake disorder (N24SWD) have a circadian rhythm that is shorter or, more often, slightly longer than 24 hours. This causes sleep and wake times to get pushed progressively earlier or later, usually by one or two hours at a time. Over days or weeks, the circadian rhythm becomes desynchronized from regular daylight hours.
As a consequence of this ever-shifting rhythm, individuals with N24SWD experience inappropriate fluctuations in appetite, mood, and alertness. During periods when their body clock is heavily desynchronized, they show a natural preference for sleeping in the middle of the day and difficulty sleeping at night. Several weeks later, they may not show any symptoms at all as their internal clock catches up with daylight once more.
Attempts to maintain a regular sleep-wake cycle are unsuccessful, even when supplemented by common solutions such as caffeine. Over the long term, desynchronization from the innate circadian rhythm may have adverse health consequences.
Individuals with non-24-hour sleep-wake disorder often have difficulty keeping work, school, or social commitments. They may develop depression6 due to the stress of not being able to keep a normal schedule, or as a side effect of sleeping during the day and not getting enough sunlight.
Excessive Daytime Sleepiness
Excessive Daytime Sleepiness (EDS)
is defined by feelings of intense grogginess during the day that can compel people to sleep at inopportune times. People who feel excessively groggy during the day may also be more prone to errors and accidents. A wide range of medical and psychological conditions can lead to EDS, such as diabetes, hypothyroidism, chronic pain, depression, and anxiety. Other causes include certain sleep disorders like sleep apnea and periodic limb movement disorder. EDS is believed to affect up to 18% of the population.
Information from the Sleep Foundation, https://www.sleepfoundation.org/sleep-disorders