Per2 mRNA expression levels in CSF cells and blood leukocytes are altered after SAH. (a) CSF Per2 mRNA expression levels were suppressed as early as day 1 after SAH compared to controls (n (controls) = 2, n = (SAH patients D1 post SAH) = 43, p = 0.008). (b) Over the course of ICU treatment, CSF Per2 expression levels remained unchanged in SAH patients (p = 0.125, F (1.256, 55.88) = 2.34). (c) Blood leukocyte Per2 mRNA expression in SAH patients were non-significantly increased compared to controls (n (controls) = 2, n (SAH patients) = 48, p = 0.059). (d) Blood leukocyte Per2 mRNA expression remained stable over the course of the following weeks (p = 0.151, F (1.39, 35.59) = 2.09). CSF: cerebrospinal fluid, Per2: Period-2, SAH: subarachnoid hemorrhage. Data presented as mean + SEM, ** p < 0.01.