Xia L, Huang L, Feng X, et al. - As acute aortic dissection (AAD) is a life-threatening emergency with poor clinical outcomes, researchers sought to determine the chronological patterns of AAD onset so that the triggers of AAD could be identified and this catastrophic event could be prevented. Among 2,048 assessed patients (mean age: 53.4±10.9 years; 80.9% male) who were diagnosed with AAD at Tongji Hospital (Wuhan, China) from 2011 to 2018, 935 cases (45.7%) were type A dissections. Comorbid hypertension/diabetes was reported in 60.3% (1,234 cases) and 1.8% (36 cases), respectively. They identified a peak in colder periods (winter/December) and a trough in warmer periods (summer/June). In Fourier analysis, a statistically significant circadian variation was observed with a nocturnal trough in 2:00–3:00, a morning peak in 9:00–10:00, and an afternoon peak in 16:00–17:00. In subgroup analyses, all subgroups showed circadian rhythmicity except the female group and younger group (younger than 55 years). Per these findings, the onset of AAD have significant seasonal, monthly and circadian patterns. Different circadian variations may be identified among patients with AAD with different Stanford-type dissections, genders, ages and hypertension statuses.