An average sleeping hours of 7 hours was recommended. It has shown to relate to the lowest rate of morbidity and mortality. Not enough sleep can make people more susceptible to pathogens. Besides sleeping duration, sleeping quality is also important because slow wave sleep (or deep sleep) helps to promote immune function. It could be done through the regulation of the actions of centrally that produced cytokines during sleeping, which help in strengthening the immune system. A totally dark sleeping environment can provide a good quality of sleeping. This is because the dark phase can stimulate the secretion of melatonin which is responsible for inducing sleeping behaviour.
Stress or anxiety lead to the changes in plasma levels of certain hormones such as epinephrine and corticosteroids. These stress-related hormones affect the immune functions and have immunosuppression effect. Yoga which emphasized on a spiritual connection between mind and body was reported to relieve stress and anxiety. This was observed with the reduction of stress hormones cortisol level after a series of yoga courses.
Immune system also can be strengthened through regular and moderate exercise. 30 to 60 minutes of aerobic exercise such as brisk walking helps to improve recirculation and function of some immune cells such as NK cells, neutrophils and macrophages. In a long term basis can improve the ability to fight against pathogens especially in a combination with healthy body weight.
A healthy and balanced diet helps to increase the efficiency of immune surveillance. Insufficient nutritional intake may weaken the immune system. Foods with high sugar, salt and saturated fat must be avoided. These components can adversely affect the immune system by promoting inflammation. On the other hand, foods rich with vitamins and minerals should be consumed more. Sufficient amounts of calories and protein are needed for optimum immune function.