Sleep is of absolute necessity for us humans, although if one falls asleep all of a sudden while being awoken, it would cause a big trouble. The brain is equipped with sleep mechanism and wakefulness mechanism, which are regulated to be on or off in an adequate manner. It is orexin*1 that is important in regulating this switch. If orexin neurons are lost, one suffers from narcolepsy*2, a sleep disorder, where sleep and wakefulness are inadequately switched on and off. The typical symptoms are excessive daytime sleepiness and cataplexy*3. Cataplexy takes place when one is very excited in terms of one's emotion and if severe, one may lose the muscle tone of the whole body and fall down. Sleep is categorized into two, REM sleep and non-REM sleep.
Dreams are dreamt usually during REM sleep, where most of the muscles are controlled to be relaxed (called atonia) in order to prevent the dreamer to make real actions. Cataplexy attack is thought that atonia, a characteristics of REM sleep, takes place while one is awoken. The research team previously found two types of neurons preventing narcolepsy by receiving orexin from orexin neurons. The one is noradrenaline neurons in the locus coeruleus of the brain, suppressing strong sleepiness, and the other is serotonin*4 neurons in the dorsal raphe nucleus of the brain, inhibiting cataplexy.
Sign up with Google
