from 8 to 12 years old. A different systematic review offers a high range of prevalence rates of sleep bruxism for children. Parasomnias like sleepwalking and talking typically occur during the first part of an individual's sleep cycle, the first slow wave of sleep During the first slow wave of sleep period of the sleep cycle the mind and body slow down causing one to feel drowsy and relaxed. At this stage it is the easiest to wake up, therefore many children do not remember what happened during this time. Nightmares are also considered a parasomnia among children, who typically remember what took place during the nightmare. However, nightmares only occur during the last stage of sleep - Rapid Eye Movement (REM) sleep. REM is the deepest stage of sleep, it is named for the host of neurological and physiological responses an individual can display during this period of the sleep cycle which are similar to being awake. 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. Another systematic review noted 7-16% of young adults have 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 greater than 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. By adulthood, parasomnias can normally be resolved due to a person's growth; however, 4% of people have recurring symptoms. Effects of Untreated Sleep Disorders Children and young adults who do not get enough sleep due to sleep disorders also have many other health problems such as obesity and physical problems where it could interfere with everyday life. It is recommended that children and young adults stick to the hours of sleep recommended by the CDC, as it helps increase mental health, physical health, and more. Insomnia Insomnia is a prevalent form of sleep deprivation. Individuals with insomnia may have problems falling asleep, staying asleep, or a combination of both resulting in hyposomnia - i.e. insufficient quantity and poor quality of sleep. Combining results from 17 studies on insomnia in China, a pooled prevalence of 15.0% is