sleep disorder sleep disorder a sleep disorder, or somnipathy, is a medical disorder of an individual's sleep patterns. some sleep disorders are severe enough to interfere with normal physical, mental, social and emotional functioning. polysomnography and actigraphy are tests commonly ordered for diagnosing sleep disorders. sleep disorderpediatric polysomnographyspecialtyclinical psychology, psychiatry, sleep medicine, neurology sleep disorders are broadly classified into dyssomnias, parasomnias, circadian rhythm sleep disorders involving the timing of sleep, and other disorders including ones caused by medical or psychological conditions. when a person struggles to fall asleep and/or stay asleep with no obvious cause, it is referred to as insomnia, the most common sleep disorder. others include sleep apnea, narcolepsy and hypersomnia (excessive sleepiness at inappropriate times), sleeping sickness (disruption of sleep cycle due to infection), sleepwalking, and night terrors. sleep disruptions can be caused by various issues, including teeth grinding (bruxism) and night terrors. management of sleep disturbances that are secondary to mental, medical or substance abuse disorders should focus on the underlying conditions. primary sleep disorders are common in both children and adults. however, there is a significant lack of awareness in children with sleep disorders, due to most cases being unidentified. several common factors involved in the onset of a sleep disorder include increased medication use, age-related changes in circadian rhythms, environmental changes, lifestyle changes, pre-diagnosed physiological problems, or stress. among the elderly, the risk of developing sleep disordered breathing, periodic limb movements, restless legs syndrome, rem sleep behavior disorders, insomnia, and circadian rhythm disturbances is especially increased. list of conditions there are a number of sleep disorders. the following list includes some of them: bruxism, involuntary grinding or clenching of the teeth while sleeping catathrenia, nocturnal groaning during prolonged exhalation delayed sleep phase disorder (dspd), inability to awaken and fall asleep at socially acceptable times but no problem with sleep maintenance, a disorder of circadian rhythms. other such disorders are advanced sleep phase disorder (aspd), non-24-hour sleep–wake disorder (non-24) in the sighted or in the blind, and irregular sleep wake rhythm, all much less common than dspd, as well as the situational shift work sleep disorder. fatal familial insomnia, an extremely rare and universally-fatal prion disease that causes a complete cessation of sleep. hypopnea syndrome, abnormally shallow breathing or slow respiratory rate while sleeping idiopathic hypersomnia, a primary, neurologic cause of long-sleeping, sharing many similarities with narcolepsy insomnia disorder (primary insomnia), chronic difficulty in falling asleep and/or maintaining sleep when no other cause is found for these symptoms. insomnia can also be comorbid with or secondary to other disorders. kleine–levin syndrome, a rare disorder characterized by persistent episodic hypersomnia and cognitive or mood changes narcolepsy, characterized by excessive daytime sleepiness (eds) and so-called "sleep attacks," relatively sudden-onset, irresistible urges to sleep, which may interfere with occupational and social commitments. about 70% of those who have narcolepsy also have cataplexy, a sudden weakness in the motor muscles that can result in collapse to the floor while retaining full conscious awareness. night terror, pavor nocturnus, sleep terror disorder, an abrupt awakening from sleep with behavior consistent with terror nocturia, a frequent need to get up and urinate at night. it differs from enuresis, or bed-wetting, in which the person does not arouse from sleep, but the bladder nevertheless empties. parasomnias, disruptive sleep-related events involving inappropriate actions during sleep, for example sleepwalking, night-terrors and catathrenia. periodic limb movements in sleep (plms), sudden involuntary movement of the arms and/or legs during sleep. in the absence of other sleep disorders, plms may cause sleep disruption and impair sleep quality, leading to periodic limb movement disorder (plmd). other limb movements in sleep, including hypneic jerks and nocturnal myoclonus. rapid eye movement sleep behavior disorder (rbd), acting out violent or dramatic dreams while in rem sleep, sometimes injuring bed partner or self (rem sleep disorder or rsd) restless legs syndrome (rls), an irresistible urge to move legs. shift work sleep disorder (swsd), a situational circadian rhythm sleep disorder. (jet lag was previously included as a situational circadian rhythm sleep disorder, but it does not appear in dsm-5, see diagnostic and statistical manual of mental disorders for more). sleep apnea, obstructive sleep apnea, obstruction of the airway during sleep, causing lack of sufficient deep sleep, often accompanied by snoring. other forms of sleep apnea are less common. obstructive sleep apnea (osa) is a medical disorder that is caused by repetitive collapse of the upper airway (back of the throat) during sleep. for the purposes of sleep studies, episodes of full upper airway collapse for at least ten seconds are called apneas. sleep paralysis, characterized by temporary paralysis of the body shortly before or after sleep. sleep paralysis may be accompanied by visual, auditory or tactile hallucinations. it is not a disorder unless severe, and is often seen as part of narcolepsy. sleepwalking or somnambulism, engaging in activities normally associated with wakefulness (such as eating or dressing), which may include walking, without the conscious knowledge of the subject. somniphobia, one cause of sleep deprivation, a dread/ fear of falling asleep or going to bed. signs of the illness include anxiety and panic attacks before and during attempts to sleep. types dyssomnias – a broad category of sleep disorders characterized by either hypersomnia or insomnia. the three major subcategories include intrinsic (i.e., arising from within the body), extrinsic (secondary to environmental conditions or various pathologic conditions), and disturbances of circadian rhythm. insomnia: insomnia may be primary or it may be comorbid with or secondary to another disorder such as a mood disorder (i.e., emotional stress, anxiety, depression) or underlying health condition (i.e., asthma, diabetes, heart disease, pregnancy or neurological conditions). primary hypersomnia: hypersomnia of central or brain origin narcolepsy: a chronic neurological disorder (or dyssomnia), which is caused by the brain's inability to control sleep and wakefulness. idiopathic hypersomnia: a chronic neurological disease similar to narcolepsy, in which there is an increased amount of fatigue and sleep during the day. patients who have idiopathic hypersomnia cannot obtain a healthy amount of sleep for a regular day of activities. this hinders the patients' ability to perform well, and patients have to deal with this for the rest of their lives. recurrent hypersomnia, including kleine–levin syndrome post traumatic hypersomnia menstrual-related hypersomnia sleep disordered breathing (sdb), including (non-exhaustive): several types of sleep apnea snoring upper airway resistance syndrome restless leg syndrome periodic limb movement disorder circadian rhythm sleep disorders delayed sleep phase disorder advanced sleep phase disorder non-24-hour sleep–wake disorder parasomnias – a category of sleep disorders that involve abnormal and unnatural movements, behaviors, emotions, perceptions, and dreams in connection with sleep. bedwetting or sleep enuresis bruxism (tooth-grinding) catathrenia – nocturnal groaning exploding head syndrome – waking up in the night hearing loud noises. sleep terror (or pavor nocturnus) – characterized by a sudden arousal from deep sleep with a scream or cry, accompanied by some behavioral manifestations of intense fear. rem sleep behavior disorder sleepwalking (or somnambulism) sleep talking (or somniloquy) sleep sex (or sexsomnia) medical or psychiatric conditions that may produce sleep disorders 22q11.2 deletion syndrome alcoholism mood disorders depression anxiety disorder nightmare disorder panic dissociative identity disorder psychosis (such as schizophrenia) sleeping sickness – a parasitic disease which can be transmitted by the tsetse fly. causes a systematic review found that traumatic childhood experiences (such as family conflict or sexual trauma) significantly increases the risk for a number of sleep disorders in adulthood, including sleep apnea, narcolepsy, and insomnia. in addition, an evidence-based synopsis suggests that idiopathic rem sleep behavior disorder (irbd) may have a hereditary component. a total of 632 participants, half with irbd and half without, completed self-report questionnaires. the results of the study suggest that people with irbd are more likely to report having a first-degree relative with the same sleep disorder than people of the same age and sex that do not have the disorder. more research needs to be conducted to further understand the hereditary nature of sleep disorders. a population susceptible to the development of sleep disorders includes people who have experienced a traumatic brain injury (tbi). because many researchers have focused on this issue, a systematic review was conducted to synthesize their findings. the results indicate that individuals who experienced a tbi are most disproportionately at risk for developing narcolepsy, obstructive sleep apnea, excessive daytime sleepiness, and insomnia. the study's complete findings can be found in the table below: source of data sleep variable community tbi community tbi sleep category nparticipants nparticipants p p z prob healthy controls sleep disturbance overall 66 85 .32 .56 3.02 .003 sleep problem sleep initiation 77 77 .05 .41 5.33 <.001 excessive daytime sleepiness 85 99 .10 .24 2.65 .008 community samples sleep disturbance overall 2187 1706 .41 .50 5.59 <.001 sleep disorders insomnia 1007 581 .10 .29 9.94 <.001 hypersomnia 7954 212 .10 .28 8.38 <.001 obstructive sleep apnoea 1741 283 .02 .25 15.51 <.001 periodic limb movements 18,980 212 .04 .08 2.95 .003 narcolepsy 18,980 152 .00b .04 17.11 <.001 sleep problem snoring 2629 65 .42 .60 3.56 <.001 insomnia 6340 1001 .31 .50 11.8 <.001 sleep maintenance 24,600 309 .27 .50 8.96 <.001 sleep efficiency 1007 119 .27 .49 4.93 <.001 sleep initiation 24,600 368 .27 .36 3.80 <.001 nightmares 2187 133 .08 .27 7.43 <.001 excessive daytime sleepiness 16,583 651 .09 .27 15.27 <.001 early morning awakening 24,600 364 .18 .38 9.76 <.001 sleepwalking 4972 99 .02 .09 4.85 <.001 sleep disorders and neurodegenerative diseases neurodegenerative diseases have often been associated with sleep disorders, mainly when they are characterized by abnormal accumulation of alpha-synuclein, such as multiple system atrophy (msa), parkinson's disease (pd) and lewy body disease (lbd). for instance, people diagnosed with pd have often presented different kinds of sleep concerns, commonly in regard to insomnia (around 70% of the pd population), hypersomnia (more than 50% of the pd population), and rem sleep behavior disorder (rbd) - that may affect around 40% of the pd population and it is associated with increased motor symptoms. furthermore, rbd has been highlighted as a strong precursor for future development of those neurodegenerative diseases over several years in prior, which seems to be a great opportunity for improving the treatments of the disease. sleep disturbances have been also observed in alzheimer's disease (ad), affecting about 45% of its population. when based on caregiver reports, this percentage increases to about 70%. as well as in pd population, insomnia and hypersomnia are frequently recognized in ad patients, which have been associated with accumulation of beta-amyloid, circadian rhythm sleep disorders (crsd) and melatonin alteration. additionally, changes in sleep architecture are observed in ad. although sleep architecture seems to naturally change with age, its development appears aggravated in ad patients. sws potentially decreases (and is sometimes absent), spindles and the length of time spent in rem sleep are also reduced, while its latency increases. poor sleep onset in ad has been associated with dream-related hallucination, increased restlessness, wandering and agitation that seem related to sundowning - a typical chronobiological phenomenon presented in the disease. the neurodegenerative conditions are commonly related to structural brain impairment, which might disrupt the states of sleep and wakefulness, circadian rhythm, motor or non motor functioning. on the other hand, sleep disturbances are frequently related to worsening patient's cognitive functioning, emotional state and quality of life. furthermore, these abnormal behavioral symptoms negatively contribute to overwhelming their relatives and caregivers. the limited research related to it and the increasing life expectancy calls for a deeper understanding of the relationship between sleep disorders and neurodegenerative disease. sleep disturbances and alzheimer's disease more than 70% of people with dementia are affected by alzheimer's disease (ad). despite this high number, our understanding of the underlying mechanisms for disease progression remains very limited. however, recent studies have highlighted a link between sleep disturbances and alzheimer's disease. sleep changes with normal aging. over time, a decrease in time sleeping and a decrease in the quantity of nrem sleep can be observed, specifically in nrem sws (less than 10% of the sws is maintained). older people also are more prone to insomnia or sleep apnea. in alzheimer's disease, in addition to cognitive decline and memory impairment, there are also significant sleep disturbances with modified sleep architecture. the latter may consist in sleep fragmentation, reduced sleep duration, insomnia, increased daytime napping, decreased quantity of some sleep stages,