They also demonstrated a loss of cardiac autonomic dynamics during sleep after stroke in addition to diurnal variation of clock gene expression and sleep–wake rhythm biomarkers.61,62 Corresponding changes are also seen in animal models of stroke; in middle-aged C57BL/6 J mice with induced M1 occlusion, compared with sham mice, sleep latency and daytime sleepiness were increased with reduced non-REM sleep duration and disruption in sleep architecture.63 The gene discussed is CLOCK; the disease is stroke disorder.