cause of sleepwalking is unknown. A number of, as yet unproven, hypotheses are suggested for why it might occur, including: delay in the maturity of the central nervous system, increased slow wave sleep, sleep deprivation, fever, and excessive tiredness. There may be a genetic component to sleepwalking. One study found that sleepwalking occurred in 45% of children who have one parent who sleepwalked, and in 60% of children if both parents sleepwalked. Thus, heritable factors may predispose an individual to sleepwalking, but expression of the behavior may also be influenced by environmental factors. Genetic studies using common fruit flies as experimental models reveal a link between night sleep and brain development mediated by evolutionary conserved transcription factors such as AP-2 Sleepwalking may be inherited as an autosomal dominant disorder with reduced penetrance. Genome-wide multipoint parametric linkage analysis for sleepwalking revealed a maximum logarithm of the odds score of 3.14 at chromosome 20q12-q13.12 between 55.6 and 61.4 cM. Sleepwalking has been hypothesized to be linked to the neurotransmitter serotonin, which also appears to be metabolized differently in migraine patients and people with Tourette syndrome, both populations being four to nine times more likely to experience an episode of sleepwalking. Hormonal fluctuations have been found to contribute to sleepwalking episodes in women, with the likeliness to sleepwalk being higher before the onset of menstruation. It also appears that hormonal changes during pregnancy decrease the likelihood of engaging in sleepwalking Medications, primarily in four classes—benzodiazepine receptor agonists and other GABA modulators, antidepressants and other serotonergic agents, antipsychotics, and β-blockers— have been associated with sleepwalking. The best evidence of medications causing sleepwalking is for Zolpidem and sodium oxybate; all other reports are based on associations noted in case reports. A number of conditions, such as Parkinson's disease, are thought to trigger sleepwalking in people without a previous history of sleepwalking. Diagnosis Polysomnography is the only accurate assessment of a sleepwalking episode. Because this is costly and sleepwalking episodes are usually infrequent, other measures commonly used include self-, parent-, or partner-report. Three common diagnostic systems that are generally used for sleepwalking disorders are International Classification of Diseases (ICD-10), the International Classification of Sleep Disorders (ICSD-3), and the Diagnostic and Statistical Manual. The Diagnostic and Statistical Manual defines two subcategories of sleepwalking, although sleepwalking does not need to involve either behaviours: sleepwalking with sleep-related eating. sleepwalking with sleep-related sexual behavior (sexsomnia). Sleep eating involves consuming food