Sub healthy state is a gray area between health and disease, characterized by a series of symptoms of decreased physical function but not yet meeting the diagnostic criteria for disease. In the fast-paced modern life, this state is becoming increasingly common, mainly manifested as persistent fatigue, which is difficult to relieve even after sufficient rest, and still feels tired when waking up in the morning, with a significant decrease in work or study efficiency. Many people may also experience sleep disorders, including difficulty falling asleep, frequent dreaming, early awakening, and some may experience fatigue despite sleeping for too long. Emotional fluctuations are another typical feature, often manifested as unnamed irritability, anxiety, or low mood. In severe cases, there may be unexplained panic, but it has not yet reached the diagnostic criteria for anxiety or depression.

Physically, sub-health individuals often experience various discomforts that are difficult to determine the exact cause. Headaches and dizziness are more common, often characterized by tension headaches or migraine like attacks; Symptoms of the digestive system, such as loss of appetite, bloating, constipation, or alternating diarrhea, are also quite common; Some people may experience symptoms of cardiac neurosis such as palpitations and chest tightness, but electrocardiograms and other examinations often do not reveal any abnormalities. Immune decline is an important characteristic of sub-health, manifested as recurrent colds, oral ulcers, slow wound healing, etc. Women may experience menstrual disorders and worsening premenstrual syndrome, while men often experience symptoms such as decreased sexual function and soreness in the waist and knees.

Cognitive function can also be affected to varying degrees, manifested as mental fatigue such as difficulty concentrating, decreased memory, and slow thinking. Some people describe it as' the brain is shrouded in a fog '. Some people may also experience increased sensory sensitivity, such as abnormal sensitivity to light and sound, or physical symptoms such as unexplained muscle soreness and joint stiffness. These symptoms often do not reveal clear organic lesions, but can significantly affect the quality of life, forming a contradictory state of "no abnormalities in examination, but feeling uncomfortable all over the body". It is worth noting that sub-health status is dynamic and may develop towards either health or disease. Timely adjustments to lifestyle are crucial for reversing this state.