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.
People who have insomnia don't feel as if they get enough sleep at night. They may have trouble falling asleep or may wake up frequently during the night or early in the morning. Insomnia is a problem if it affects your daytime activities. Insomnia has many possible causes, including stress, anxiety, depression, poor sleep habits, circadian rhythm disorders (such as jet lag), and taking certain medications.
Interestingly, the glymphatic cleanrance occurs during the NREM sleep, and more specifically the NREM SWS sleep. As seen previously, it is a sleep stage that decreases in normal aging. So there is less glymphatic clearance and an increase in AB burden that will form the AB plaques. Therefor, in AD sleep disturbances will amplify this phenomenon.
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.
Narcolepsy is a brain disorder that causes excessive daytime sleepiness. There is sometimes a genetic component, but most patients have no family history of the problem. Though dramatic and uncontrolled "sleep attacks" have been the best-known feature of narcolepsy, in reality many patients do not have sleep attacks. Instead, they experience constant sleepiness during the day.
Another systematic review noted 7-16% of young adults suffer from delayed sleep phase disorder. This disorder reaches peak prevalence when people are in their 20s. Between 20 and 26% of adolescents report a sleep onset latency of >30 minutes. Also, 7-36% have difficulty initiating sleep. Asian teens tend to have a higher prevalence of all of these adverse sleep outcomes than their North American and European counterparts.
A nocturnal movement disorder, restless leg syndrome can feel like itchiness, tingling, or prickling that makes you feel like you have to move your legs. Your legs may also move without your control while you sleep. You may or may not be aware of waking during the night, but restless leg syndrome causes sleep problems by preventing deep, restful sleep.