Patients suddenly faint in the middle of the night when they get up to go to the toilet, there are actually many reasons for this condition, which is also called syncope. In clinical practice, the common causes of syncope are cardiogenic or cerebrogenic causes, such as cerebral atherosclerosis, cerebral vascular stenosis and other factors that cause transient cerebral blood supply and cerebral perfusion deficiency, which can lead to transient loss of consciousness. It can be determined by checking transcranial Doppler, magnetic resonance brain function imaging, angiography and other examinations to clarify. There is also cardiogenic syncope, such as common paroxysmal arrhythmias, frequent premature ventricular beats, or transient syncope caused by transient cardiac arrest. This is a more serious problem, and a 24-hour ambulatory ECG can be performed to observe the rhythm of the patient’s heartbeat. Vagal syncope should also be considered, which usually occurs when the patient urinates, defecates, etc.