As suggested by its name, PLMD is an involuntary movement disorder. (An older name, nocturnal myoclonus , is rarely used anymore.) People with this problem experience sudden, involuntary leg movements during the night, such as kicking or jerking. The difference between this and restless leg syndrome is that, unless the kicking wakes you up, you don't know you're doing it. You don't experience the tingling and discomfort that leads you to consciously move your legs, as with restless leg syndrome. At least 80 percent of people with restless leg syndrome have PLMD, but the reverse isn't true.
The natural internal clock that controls our 24-hour cycle of sleep and waking, circadian rhythms are easily upset by changes in schedule, and they're greatly affected by light and darkness. Jet lag is the best known circadian rhythm disorder, but this sensitive inner clock can also be disrupted by changes in routine resulting in an erratic sleep schedule.
In people who have restless legs syndrome, discomfort in the legs and feet peaks during the evening and night. They feel an urge to move their legs and feet to get temporary relief, often with excessive, rhythmic, or cyclic leg movements during sleep. This can delay sleep onset and cause brief awakening during sleep. Restless legs syndrome is a common problem among middle-aged and older adults.

According to one meta-analysis, the two most prevalent sleep disorders among children are confusional arousals and sleep walking.[57] An estimated 17.3% of kids between 3 and 13 years old experience confusional arousals.[57] About 17% of children sleep walk, with the disorder being more common among boys than girls.[57] The peak ages of sleep walking are from 8 to 12 years old.[57] A different systematic review offers a high range of prevalence rates of sleep bruxism for children. Between 15.29 and 38.6% of preschoolers grind their teeth at least one night a week. All but one of the included studies reports decreasing bruxist prevalence as age increased as well as a higher prevalence among boys than girls.[58]

In the UK, knowledge of sleep medicine and possibilities for diagnosis and treatment seem to lag. quotes the director of the Imperial College Healthcare Sleep Centre: "One problem is that there has been relatively little training in sleep medicine in this country – certainly there is no structured training for sleep physicians."[55] The Imperial College Healthcare site[56] shows attention to obstructive sleep apnea syndrome (OSA) and very few other sleep disorders. Some NHS trusts have specialist clinics for respiratory and/or neurological sleep medicine.
Chronic sleep disorders in childhood, which affect some 70% of children with developmental or psychological disorders, are under-reported and under-treated. Sleep-phase disruption is also common among adolescents, whose school schedules are often incompatible with their natural circadian rhythm. Effective treatment begins with careful diagnosis using sleep diaries and perhaps sleep studies. Modifications in sleep hygiene may resolve the problem, but medical treatment is often warranted.[35]
Throughout the decades as more research and studies were conducted, the amount of sleep disorders being discovered began to rapidly increase. In 1990 The AASM, along with other professional societies including the European Sleep Research Society, The Japanese Society of Sleep Research, and the Latin American Sleep Society published the International Classification of Sleep Disorders (ICSD), which is a "primary diagnostic, epidemiological, and coding resource for clinicians and researchers in the field of sleep and sleep medicine."
Recent studies, however, have shown that several factors can interrupt this neurogenesis.[29] These include stress and prolonged sleep deprivation (more than one day).[29] The sleep disturbances encountered in AD could therefore suppress neurogenesis and thus impairing hippocampal functions.[29] This would therefore contribute to diminished memory performances and the progression of AD.[29] And progression of AD would aggravate sleep disturbances.[29] It is a second vicious circle.  
Insomnias This type of sleep disorder involves the inability to fall asleep or stay asleep. MORE>>Hypersomnias Hypersomnias are a group of sleep disorders that causes a person to be excessively sleepy. People with a hypersomnia may fall asleep at times that are inconvenient or even dangerous, such as at work or while driving. MORE>>Sleep Related Breathing Disorders Sleep disorders that involve difficulty breathing during sleep are classified as sleep related breathing disorders. Obstructive sleep apnea is the most common disorder of this type, however there are a number of variations of sleep apnea. MORE>>Circadian Rhythm Sleep-Wake Disorders Conditions in which the sleep times are out of alignment. A patient with one of these disorders does not follow the normal sleep times at night. MORE>>Parasomnias Parasomnias are a group of sleep disorders that involve unwanted events or experiences that occur while you are falling asleep, sleeping or waking up. MORE>>Sleep Movement Disorders This classification of sleep disorders includes conditions that cause movement during or prior to sleep. These disorders can make it difficult to fall asleep or stay asleep, or to get restful sleep. MORE>>
Combining results from 17 studies on insomnia in China, a pooled prevalence of 15.0% is reported for the country.[60] This is considerably lower than a series of Western countries (50.5% in Poland, 37.2% in France and Italy, 27.1% in USA).[60] However, the result is consistent among other East Asian countries. Men and women residing in China experience insomnia at similar rates.[60] A separate meta-analysis focusing on this sleeping disorder in the elderly mentions that those with more than one physical or psychiatric malady experience it at a 60% higher rate than those with one condition or less. It also notes a higher prevalence of insomnia in women over the age of 50 than their male counterparts.[61]
Even if you’ve struggled with sleep problems for so long that it seems normal, you can still learn to sleep better. You can start by tracking your symptoms and sleep patterns, and then making healthy changes to your daytime habits and bedtime routine. If self-help doesn’t do the trick, you can turn to sleep specialists who are trained in sleep medicine. Together, you can identify the underlying causes of your sleeping problem and find ways to improve your sleep and quality of life.

The neurodegenerative conditions are commonly related to brain structures impairment, which might disrupt the states of sleep and wakefulness, circadian rhythm, motor or non motor functioning.[22][24] On the other hand, sleep disturbances are also frequently related to worsening patient's cognitive functioning, emotional state and quality of life.[24][27][28] Furthermore, these abnormal behavioural symptoms negatively contribute to overwhelming their relatives and caregivers.[24][27][28] Therefore, a deeper understanding of the relationship between sleep disorders and neurodegenerative diseases seems to be extremely important, mainly considering the limited research related to it and the increasing expectancy of life.[22][28]
If sleeping with a mask on doesn't work for you, other options are surgery; oral appliances; and newer, minimally invasive outpatient surgical treatments. These include the Pillar procedure, which involves using permanent stitches to firm up the soft palate; coblation, which uses radiofrequency to shrink nasal tissues; and even use of a carbon dioxide laser to shrink the tonsils.