Objectives: Hypertension continues to cause significant morbidity and mortality worldwide, and the situation is worse in Blacks. Treatment has proved to be beneficial, but control has remained abysmal. Night-time chronotherapy is producing better control and outcome, but has only largely been tried in the West. This work attempts to see what benefits would emerge with night-time chronotherapy as compared with the current recommended morning intake of antihypertensives in an entirely African cohort.

Methods: Ambulant grade 1 and 2 hypertensives attending our outpatient service were randomized after a washout period into morning or night-time ingestion groups. Drugs were tailored towards each patient's cardiovascular disease profile and reviewed to ensure control. They were comprehensively evaluated on enrolment and 12 weeks later.

Results: Both groups were similar on all scores at baseline. After 12 weeks of treatment, the mean changes in diastolic blood pressure (DBP), mean arterial pressure (MAP), left ventricular posterior diameter (LVPWD) and left ventricular mass (LVM) were greater, to a statistically significant extent in the night-time group. The difference in the systolic blood pressure (SBP) and interventricular septum diameter (IVSD) tended to be greater in the same group but did not differ between the groups to a statistically significant extent.

Conclusion: Chronotherapeutic studies in the West recorded greater success with night-time ingestion which produced better control and a day-long profile. Generalization to other races was cautioned against until such observations could be replicated. We have shown that patients using their once-daily antihypertensives at night after 12 weeks recorded better reductions in SBP, DBP, MAP, LVPWD, IVSD and LVM. Since blood pressure problems run a worse course in Blacks, we recommend encouragement of night-time intake in those preferring it and suggest that in those requiring two or more drugs one should be taken at night.