If you sleep at night with your arms around your neck or your chest, you will have poor breathing and nightmares. These nightmares are often manifested by images such as snakes and boulders or scary things to remind you in your dreams, so that you can wake up as soon as possible and change your posture. This is completely the embodiment of the subconscious self-protection mechanism. You should understand this explanation. Even when we are asleep, the subconscious will protect us from harm. For another example, if you fall asleep and fall out of bed, you won't feel any pain at all, which is also a kind of self-protection of the subconscious mind.