功能内稳态(FSH)通过利用负反馈机制维持功能特异的条件来实现功能的充分发挥。低水平光(LLL)所定义的单色光或激光对处于FSH的功能没有调节作用,但可以调节远离FSH的功能。FSH的品质包括功能的复杂性和FSH的稳定性。FSH的稳定性由介导寿命延长作用的长寿因子维持。功能复杂性与FSH稳定性之间彼此适应,因此存在FSH特异的长寿因子活性。对研究最多的长寿因子组蛋白去乙酰化酶(SIRTs),也存在FSH特异的SIRTs活性(FSSA)。FSH的品质越高,FSSA越高。如果细胞的SIRTs活性低于FSSA,LLL可以提高SIRTs活性直到达到FSSA。如果SIRTs活性稍高于FSSA但细胞能够回复到FSH,LLL可以通过提高其他细胞的SIRTs活性促进这些细胞康复到FSH。如果SIRTs活性远远高于FSSA,LLL促进具有更高FSSA的新的FSH的建立。总之,LLL的细胞康复作用是由SIRTs介导的。

Function-specific homeostasis (FSH) is a negative-feedback response of a biosystem to maintain the function-specific conditions inside the biosystem so that the function is perfectly performed. Low level light (LLL) is so defined that it can not modulate the function in its FSH,but it can modulate the function far from its FSH. FSH quality is represented by function complexity and FSH stability. The FSH stability is maintained by longevity factors which mediate longevity extension. The function complexity and FSH stability are specific with each other so that there is FSH-specific longevity factor activity for each one. Among the longevity factors,sirtuins (SIRTs) are the most famous family. There is FSH-specific SIRT activities (FSSA). The FSSA increase as the FSH quality goes up. For the cells which SIRT activities are lower than FSSA,LLL may increase SIRT activities until the SIRT activities arrive at FSSA,respectively. For the cells which SIRT activities are higher than FSSA,respectively,but they can be back in FSH,LLL may increase the SIRT activities of the other cells,which promotes the rehabilitation of the cells so that they may be back in FSH. For the cells which SIRT activities are much higher than FSSA,respectively,LLL may promote the establishment of a new FSH of higher FSSA. In summary,the cellular optical rehabilitation may be mediated by SIRTs.