Postural arrhythmias refer to a variety of heartbeat irregularities that occur due to changes in body position and can occur in healthy individuals without any medical conditions or in patients with heart disease. There are many types of arrhythmias that can occur with postural arrhythmias. For example, some healthy young people can have a slow heartbeat (conduction block, even sinus arrest, etc.) at night in right lateral recumbency, while a left lateral recumbency followed by an ambulatory electrocardiogram reveals a significant improvement in the apparent slow heartbeat. In some patients with ventricular premature beats, however, an increase in ventricular premature beats was found in the left lateral recumbent position and a significant decrease in the flat, right lateral recumbent position. Some patients even have arrhythmias that start while lying down and disappear completely when they stand up. Why is this? Because all organs of the body are often innervated by sympathetic and parasympathetic nerves, two pairs of nerves with opposite effects. When the sympathetic nerve is excited, the manifestations are: pupil dilatation, heart rate increases, skin and visceral vasoconstriction, coronary artery dilation, blood pressure rises, small bronchial diastole, gastrointestinal peristalsis weakens, bladder wall muscle relaxation, saliva secretion decreases, sweat glands secrete sweat, lissimus muscle contraction, etc. When the body is in a state of nervous activity, sympathetic nerve activity plays a major role. When the vagus nerve is excited, it is manifested as follows: ① Enhancement of gastrointestinal activity, secretion of digestive glands, promotion of urinary and fecal excretion, and maintenance of body energy. (ii) Pupil narrowing to reduce stimulation and promote hepatic glycogen production to save energy. (3) Heartbeat slows down, blood pressure decreases, and bronchi narrow to save unnecessary consumption and to assist reproductive activities, such as causing dilation of reproductive blood vessels and increased secretion of fluids from sexual organs. The heart is innervated by both of these nerves so that the blood supply can be well regulated according to the body’s needs. Some arrhythmias can also be caused by one of these nerves being excited and dominating, leading to an arrhythmia attack, for example, atrial fibrillation, which often occurs at night, is often caused by vagal excitation, while sympathetic excitation can often cause ventricular tachycardia, electrical storms, etc. So if we say that different nerve excitations can cause different arrhythmias, can different nerves dominate or increase their excitability by changing the sleeping position? Yes, the distribution and innervation of the sympathetic and vagus nerves in the heart are actually not symmetrical. The sympathetic nerve is mainly located on the right side of the heart, right at its position in the paravertebral perineurium, while the vagus nerve is mainly located on the left side of the heart, with fibers emanating from the medulla oblongata of the brainstem to the ganglion perineurium next to the heart. In the left lateral recumbent position, the sympathetic nerve can be excited, while in the right lateral recumbent position, the vagus nerve is excited. And sympathetic nerves dominate when upright and vagus nerves dominate when lying down, so that different sleeping positions can lead to different arrhythmias. But sleeping position not only affects arrhythmia, but also affects the performance of several organs, for example: sleeping on the left side will make the amount of acidic fluid reflux from the stomach to the esophagus much higher than normal and constant, which will easily cause burning pain in the stomach and thus predispose to gastric disease. Patients suffering from esophageal reflux, a digestive dysfunction, are better off sleeping on their left side. Sleeping on the side can make cerebral infarction patients with existing atherosclerosis itself aggravate the blood flow disorder, especially the slowing down of blood flow in the neck, which is prone to the formation of thrombus by gathering at the arterial intima injury. In order to eliminate the hidden danger of cerebral thrombosis, it is more appropriate to choose the appropriate pillow height and sleep on your back. Low pillow will increase the blood flow in the brain, which will promote the formation of hypertension over time, and too high will also feel uncomfortable. It is advisable to use a flat sleep position with a pillow, the pillow is generally about 15 cm high. Supine position supine position, the limbs and bed contact area is the largest, and therefore not easy to fatigue, and is conducive to the blood circulation of the limbs and brain. However, some middle-aged and elderly people, especially the more obese elderly, in the supine position is easy to make the root of the tongue fall backward, causing poor breathing and snoring, heavy snoring will not only affect the rest of others, but also affect the exchange of gas in the lungs caused by hypoxemia. Therefore, it depends on the actual need for the specific kind of lying position.