Due to rapidly increasing knowledge about sleep in the 20th century, including the discovery of REM sleep in the 1950s and circadian rhythm disorders in the 70s and 80s, the medical importance of sleep was recognized. The medical community began paying more attention than previously to primary sleep disorders, such as sleep apnea, as well as the role and quality of sleep in other conditions. By the 1970s in the US, clinics and laboratories devoted to the study of sleep and sleep disorders had been founded, and a need for standards arose.
One factors that could explain this change in sleep architecture is a change in circadian rhythm, which regulates sleep. A disruption of the circadian rhythm would therefore generate sleep disturbances. Some studies show that people with AD have a delayed circadian rhythm, whereas in normal aging we will find an advanced circadian rhythm.
Waking up in the middle of the night to use the bathroom is such a common problem it has a name: nocturia . As we get older, our bodies' ability to hold fluids for long periods decreases, thanks to a decline in antidiuretic hormones. According to the National Sleep Foundation, 65 percent of older adults have sleep deprivation resulting from waking up frequently to use the bathroom.
This clock is a small part of the brain called the suprachiasmatic nucleus of the hypothalamus. It sits just above the nerves leaving the back of our eyes. Light and exercise "reset" the clock and can move it forward or backward. Abnormalities related to this clock are called circadian rhythm disorders ("circa" means "about," and "dies" means "day").
Some of the biggest differences between the 2nd and 3rd editions are how the various sleep disorders were divided into categories. The 2005 edition used 3 broad categories to organize all of the sleep disorders under either dysommnias (disorders making getting to sleep or staying asleep difficult), parasomnias (disorders that intrude into the sleep process), and sleep disorders associated with a mental, neurologic, or other medical disorders (disorders whose symptoms are not primary unto themselves but caused by other conditions).
Neurodegenerative diseases have been often 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 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. Importantly, RBD has been also highlighted as a strong precursor of developing dementia in PD patients over several years in prior, which seems to be a great opportunity for improving the treatments of the disease.
In Alzheimer's disease, in addition to cognitive decline and memory impairment, there is also significant sleep disturbances with a modified sleep architecture. The latter may consist in sleep fragmentation, a reduction in sleep duration, insomnia, an increase daytime naping, a decreased quantity og some sleep stages and a resemblance between some sleep stages (N1 and N2). More than 65% of people with Alzheimer's disease suffer from this type of sleep disturbance.
In addressing sleep disorders and possible solutions, there is often a lot of buzz surrounding melatonin. Research suggests that melatonin is useful in helping people to fall asleep faster (decreased sleep latency), to stay asleep longer, and to experience improved sleep quality. In order to test this, a study was conducted that compared subjects that had taken Melatonin to subjects that had taken a placebo pill in subjects with primary sleep disorders. Researchers assessed sleep onset latency, total minutes slept, and overall sleep quality in the Melatonin and placebo groups to note the differences. In the end, researchers found that melatonin decreased sleep onset latency, increased total sleep time, and improved quality of sleep significantly more than the placebo group.
In addition, an evidence-based synopses suggests that the sleep disorder, idiopathic REM sleep behavior disorder (iRBD), may have a hereditary component to it. 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 gain further information about the hereditary nature of sleep disorders.
There are many possible causes of restless legs syndrome, including kidney failure, nerve disorders, vitamin and iron deficiencies, pregnancy, and some medications (such as antidepressants). Recent studies have shown a strong genetic link and researchers have been able to isolate a gene that may be responsible for at least 40% of all cases of the disorder.
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. It is currently unclear whether or not moderate alcohol consumption increases the risk of obstructive sleep apnea.
A systematic review states 7.6% of the general population experiences sleep paralysis at least once in their lifetime. Its prevalence among men is 15.9% while 18.9% of women experience it. When considering specific populations, 28.3% of students and 31.9% of psychiatric patients have experienced this phenomenon at least once in their lifetime. Of those psychiatric patients, 34.6% have panic disorder. Sleep paralysis in students is slightly more prevalent for those of Asian descent (39.9%) than other ethnicities (Hispanic: 34.5%, African descent: 31.4%, Caucasian 30.8%).
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.
Primary sleep disorders are most common in men and women over the age of 65. About half of the people claim to have some sleep problem at one point. It is most common in the elderly because of multiple factors. Factors include increased medication use, age-related changes in circadian rhythms, environmental and lifestyle changes  and pre diagnosed physiological problems and stress. The risk of developing sleep disorders in the elderly is especially increased for sleep disordered breathing, periodic limb movements, lestless legs syndrome, REM sleep behavior disorders, insomnia and circadian rhythm disturbances.
If your snoring is loud and uneven, erupts in snorts, or you sound like you're catching your breath or there are gaps in your breathing, these are signs of obstructive sleep apnea, the most severe type of sleep-disordered breathing. People with sleep apnea stop breathing repeatedly during their sleep because of a blockage in the mouth or throat, most commonly the soft tissues in the back of the throat, which collapse and close off.