As the saying goes, "three inches long life, four inches worry-free", what do "three inches" and "four inches" mean here?

"Three inches long life, four inches worry-free" means the height of the pillow. The height of three inches is about 10 cm, while the height of four inches is about 13 cm, which is just about 10 cm to 13 cm, so there will be such a statement.

Because the height of 10 cm to 13 cm is just in line with the human body structure, if it is too low, the neck may lean back when lying flat, and if it is too high, the spine will bend. Therefore, after long-term life, the ancients concluded that the height of the pillow is three inches to four inches.

Ancient pillows are different from modern ones. In ancient times, pillows were made of wood or jade, and they were all hard objects. Generally, ordinary people's homes were made of wood, and large families or courts would be made of jade. In ancient times, the classification of pillows was also varied. The ancients once divided pillows into winter pillows, summer pillows or soft pillows and hard pillows.

In addition to the height of the pillow, it is also important to keep the head in a reasonable position on the pillow when sleeping. Generally speaking, it is best to put the head above the center of the pillow, so as to stabilize the sleeping position, avoid stiff neck caused by frequent posture change at night, give a certain support to the neck and maintain the normal physiological curve of the body.

The ancient pillows were hard, because hard pillows were good for human health. However, the contact surface between the head and the pillow is too small and the local pressure is too great, which makes people feel uncomfortable. Obviously, after a night's sleep, there will be symptoms of numbness or pain in the head, neck, back, arms and hands the next morning.

Therefore, a seemingly simple pillow contains a lot of knowledge. Choosing a pillow that suits you is the guarantee of reorganizing sleep.