免疫力下降
若是经常熬夜，人体的正常代谢功能就会受到影响，这就是为何人在熬夜后容易出现疲劳、精神不振等状态。所以，如果不及时调理，人的免疫力就会随之下降。
那么免疫力下降会导致什么问题呢？人体的免疫功能若下降，就会出现感冒、肠胃不适、皮肤问题、精神不佳等症状。
美国一项新研究发现，人体生理反应的节奏跟昼夜交替一致，一旦这个节奏被破坏，人们免疫系统的抗病能力就会降低。研究者美国得克萨斯大学西南医学中心免疫学博士于肖飞说：“这一研究成果不仅在分子水平上揭示了昼夜交替如何影响机体免疫系统，也有助于我们更有效地利用自身免疫功能来对抗感染或者预防免疫疾病。”
中医认为“人卧则血归肝”，夜晚11点到凌晨3点是肝藏排毒与解毒的最佳阶段，这个时间若不按时休息，久而久之就会损伤肝气，同时亦会降低抵抗力和免疫力的功能。
此外，长时间的睡眠不足，免疫系统功能则会受体内荷尔蒙的影响。因为晚上睡觉的时候，生长激素（growth hormone）、泌乳素（prolactin）与褪黑激素（melatonin）的分泌量会上升，而这些荷尔蒙会有共同作用，促进免疫細胞的生长与分化；另一方面，肾上腺皮质醇（cortisol）与肾上腺素（epinephine）这类会抑制免疫功能的荷尔蒙分泌量在睡觉的时候就会减少。
Decline Immune system
If you often stay up late, the body's metabolic function will be affected. That is why people are prone to fatigue and lethargy. So, if this is not adjusted in time, the body immunity will decline.
What problems do we face when the immune system decreases? If the immune system is not functioning properly, it will cause cold, gastrointestinal discomfort, skin problems, poor mental symptoms and so on.
A new study in the United States found that the rhythm of the human physiological response coincided with that of the day and night. So, once the rhythm is disrupted, our resistance will be reduced. Yu Xiao Fei, the doctor of Immunology at University of Texas Southwestern Medical Centre, said: “This study reveals not only how day and night alternation affects the immune system at the molecular level, it also helps us to use our own immune function more effectively to fight infection or prevent immunization.”
Chinese medicine believes that the blood flows back to the liver when we lie down and the best time for liver detoxification and detoxification is from 11 p.m. to 3 a.m. So, if we do not rest on time, the liver will be damaged over time. The resistance and immunity function will also be reduced.
In addition, if the lack of sleep continues for a long time, the function of the immune system will be affected by the hormones. When we sleep at night, the growth hormone, prolactin and melatonin secretion will rise, and these hormones will have a common role in promoting the growth and differentiation of immune cells. On the other hand, adrenal cortisol and adrenaline, which inhibit the immune function of hormonal secretion during sleep time, will be reduced.