Both night terrors and sleepwalking arise during NREM sleep and occur most often in children between the ages of 3 and 5 years old. A night terror can be dramatic: Your child may wake up screaming, but unable to explain the fear. Sometimes children who have night terrors remember a frightening image, but often they remember nothing. Night terrors are often more frightening for parents than for their child. Sleepwalkers can perform a range of activities -- some potentially dangerous, like leaving the house -- while they continue to sleep.
Sleep apnea is a common (and treatable) sleep disorder in which your breathing temporarily stops during sleep, awakening you frequently. If you have sleep apnea you may not remember these awakenings, but you’ll likely feel exhausted during the day, irritable and depressed, or see a decrease in your productivity. Sleep apnea is a serious and potentially life-threatening sleep disorder, so see a doctor right away and learn how to help yourself.

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.
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]
Interestingly, it has been shown that the sleep-wake cycle acts on the beta-amyloid burden which is a central component found in AD.[29][30] Indeed, during waking, the production of beta-amyloid protein will be more consistent than during sleep.[29][30][32] This is explained by two phenomena. The first is that the metabolic activity will be higher during waking and thus will secrete more beta-amyloid protein.[29][30] The second is that oxidative stress will also be higher and lead to increased AB production.[29][30]
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]
Restless leg syndrome (RLS) is an overwhelming need to move the legs. This urge is sometimes accompanied by a tingling sensation in the legs. While these symptoms can occur during the day, they are most prevalent at night. RLS is often associated with certain health conditions, including ADHD and Parkinson’s disease, but the exact cause isn’t always known.

Keep a pen and paper next to your bed. If you're often kept awake by racing thoughts and worries and you tend to make to-do lists in your head, keep a pen or pencil and a small pad of paper handy and write them down. As you put each item down on paper, imagine yourself setting aside that concern. (Again, use a book light; don't turn on the overhead or a bright bedside light to write.)