According to the standard of sleep staging, the normal proportion of deep sleep time for adults to total overnight sleep time is 13% to 23%. That is to say, if the overnight sleep time is 6-7 hours, a deep sleep time of 50 minutes is normal. As age increases, the proportion of deep sleep time gradually decreases, which is a normal physiological change. Healthy individuals can easily judge their sleep quality based on their own state, such as asking themselves: How is my mental state during the day? Can you handle work and life matters normally? If daytime function is normal, it means you have high-quality sleep. Everyone can ensure deep sleep time by cultivating healthy sleep habits. For example, try to maintain a regular daily routine, increase sunlight during the day, engage in appropriate physical exercise, and limit the intake of stimulating drinks such as tea and coffee after the afternoon. The most important thing is to relax both body and mind. Here, we recommend a very useful relaxation method, which is the "progressive relaxation exercise": lie flat on the bed, gently close your eyes, take a few deep breaths first, then bring your attention to the top of your head, imagine the top of your head gradually relaxing, and then use this method to relax the head, neck, shoulders, upper limbs, chest, abdomen, back, lower limbs and other parts in sequence. Relaxing every part from head to toe can help us enter deep sleep better. (New Society)