Describe the major sleep disorders?

Generally there are 4 types of major sleep disorders. The first and the most widely known types of sleep disorder is the insomnia, this kind of sleep disorder cause some people to have difficulty in sleeping. the second type is called apnea, people experiencing this kind of disorder causes their breathing to be interrupted during sleep thus making apnea a potential serious sleep disorder. The third would be the restless legs syndrome, this disorder cause some people to intensively move their legs while they are asleep. And the fourth commonly known sleep disorder would be the narcolepsy, this kind of sleep disorder, unlike the first three mentioned earlier, causes the person to experience excessive daytime sleepiness or sometimes falling asleep during daytime uncontrollably.