Background The role of circadian rhythm of energy and macronutrient intake in influencing cardiometabolic risk factors is increasingly recognised. However, little is known of the association between time of energy intake and long-term risk of hypertension.

Objectives To examine the association between time of day of energy intake and risk of hypertension.

Methods The analysis included 517 men and 635 women who were members of the MRC National Survey of Health and Development (1946 British birth cohort). Diet was assessed using 5d estimated diaries at ages 43 years (1989) and 53 years (1999). Diet diaries were divided into seven time slots: breakfast, mid-morning, lunch, mid-afternoon, evening, night and extra. The association between time of day of energy intake in 1989 or 1999 and blood pressure in 1999 was assessed using logistic regression after adjustment for sex, social class, smoking status, region and body mass index. Hypertension was defined by systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg.

Results Compared to the lowest quintile, cohort members from the highest quintile of energy intake at night in 1989 were more likely to have high systolic (OR=1.69; 95% CI 1.08 to 2.7; p=0.024) but not high diastolic blood pressure in 1999 (OR=1.64; 95% CI 1.02 to 2.66; p=0.055). Energy intake at night in 1999 was not related to high systolic or diastolic blood pressure in 1999. No associations between energy intake at other time slots and hypertension were observed.

Conclusions Increased energy intake at night is predictive of higher risk of systolic hypertension 10 years later.