There is no scientific basis for the tendency to have nightmares with your hand on your chest. Dreams occur during the non-REM period of sleep. Hands on the chest will be a physical pressure on the thorax, may lead to sensations in sleep, but there is no scientific evidence to cause nightmares. Nightmares are seen in depression, anxiety, insomnia, there will be autonomic dysfunction, neurasthenia. External stimuli can also cause shallow sleep, dreamy. If you drink alcohol, you will also be prone to nightmares. You should ensure good work and rest habits, avoid doing strenuous exercise before going to bed, and don’t read scary novels, movies, etc. before going to bed. Do something relaxing before going to bed, such as drinking milk, soaking your feet, taking a hot bath, and so on.