Fig. 4
From: The mammalian circadian clock and its entrainment by stress and exercise
Decreased amplitude of PER2::LUC rhythms in peripheral tissues after daily caffeine injections. a Experimental schedule; mice were maintained under 12:12 h light–dark conditions and given intraperitoneal (IP) injections of saline (control; VEH) or 20 mg kg−1 caffeine (CAF) for 3 consecutive days at Zeitgeber time (ZT)1; in vivo monitoring was initiated at ZT9. b Normalized waveforms of PER2::LUC rhythms in saline- or caffeine-injected mice