Disclosed is a method for providing information used for comparing restoration rates of damaged DNA, wherein information about a time period when Ataxia telangiectasia and Rad3 related (‘ATR’) activation is accelerated, on the basis of alternative information about an expression level of cryptochrome may be acquired, therefore, it can be determined that a restoration rate of damaged DNA is high at a time period when the expression level of cryptochrome is high. Accordingly, a time period when a restoration rate of DNA damaged by different causes is high, can be determined. Further, it is possible to estimate a time period when side effects occurring due to using an anticancer drug are minimized, and then, utilize the estimated result in determining the timing of administration of an anticancer drug.