Hey!
No, you aren't supposed to cycle Casein. In the case of Creatine, your body naturally adapts to the effects of Creatine over a certain period of use. Casein on the other hand, is just a supplement to provide your body with fuel during your sleep (equivalent to eating food such as cottage cheese). Your body doesn't "adapt" to you eating before bed (such as a Casein shake). Hope that helped out!