The Effect of 6 Months of Dietary Counselling on Sleep Outcomes Among Patients With Cardiovascular Diseases: A Randomised Controlled Trial.

Sleep problems are highly prevalent among patients with cardiovascular diseases (CVD). We examined the effect of dietary counselling on sleep outcomes among patients with CVD. We performed secondary analyses within a previously conducted six-month randomised controlled trial among patients with CVD. Within the trial, the intervention group received dietary counselling aimed to increase adherence to the Dutch dietary guidelines and the control group received usual care. Diet quality was assessed with an index, in which higher scores (range 0-160) indicated better adherence. Sleep outcomes were assessed with the Pittsburgh Sleep Quality Index. An overall score > 5 was classified as a poor sleep quality. Among the 112 patients with CVD included in these analyses (68.9 ± 9.2 years; 74% male; 27.7 ± 4.0 kg/m2), 32% had a poor sleep quality at baseline. Diet quality seemed to improve more in the intervention group (from 104.7 ± 16.5 to 117.0 ± 16.1) than in the control group (from 102.1 ± 22.2 to 107.7 ± 19.7). The intervention did not result in statistically significant differential changes over time between the intervention (n = 57) and control group (n = 55) for sleep quality (0.2 points on overall PSQI; 95% CI -0.6, 1.0), sleep duration (9.0 min; 95% CI -15.8, 33.8), sleep onset latency (3.8 min; 95% CI -3.5, 11.1), or sleep efficiency (-0.2%; 95% CI -4.0, 3.7). To conclude, counselling on a healthy diet did not result in better sleep outcomes among patients with CVD. Improvements in diet quality within this study might have been insufficient to affect sleep, or improving diet quality might not affect sleep among patients with CVD.