Many people think that the quality of sleep is not good if you dream a lot and think that a dreamless night is the best sleep. If you are awakened while dreaming, you will feel as if you have not slept. In the past, sleeping pills only let people sleep but not dream, so patients often complain as if they have not even slept, so is dreaming necessary or not? In daily life we often find that if a few days in a row a dream to wake up, the next, as soon as you fall asleep immediately dream, so dreaming is necessary or not? Someone once made an interesting experiment: he used the method of EEG recording to compare two groups of people. In the first group, when REM sleep (rapid eye movement sleep) appeared on the EEG, the subject was awakened and then put to sleep after a few minutes; at the same time, another group was awakened during NREM sleep (deeper sleep), and the two groups were awakened at the same time as much as possible, only the period of sleep was different. After several nights, the first group of people had surprisingly more and more REM sleep, and by the end of the experiment, when they were allowed to resume their previous sleep patterns, the number of REM sleep had to reach twice the usual number, while the second group showed no change in their REM sleep on the EEG, no matter during waking or after resuming normal sleep. This indicates that the first group was always awakened during dreaming and was missing the “dream”, so the REM sleep was increased to make up for the “dream”. In contrast, the second group woke up during the sleep when they were not dreaming, they were not missing “dreams” (REM sleep), and they did not need to make up “dreams”. This experiment confirms the necessity of dreaming, and that 4-6 dreams per night are necessary.