Rationale Sleep is an emerging risk factor for cardiovascular disease (CVD). We examined the relationship between sleep duration and haemostatic factors important in CVD development, in a well-characterised occupational cohort.
Methodology The relationship between self-reported sleep duration and von Willebrand factor (vWF), fibrinogen and factor VII in 6400 individuals from the Whitehall II study was examined.
Results Owing to significant gender interactions (p<0.001), the analysis was stratified by gender. After multiple adjustments, vWF levels were significantly higher in men with both short (<6 h per night; 1.05 (95% CI 1.01 to 1.08)) and long (>8 h per night; 1.05 (95% CI 1.02 to 1.08)) duration of sleep compared with those who slept 7 h (p<0.05 for both). In women, levels of vWF were significantly higher in individuals who slept >8 h (1.11 (95% CI 1.06 to 1.16)) than in those who slept for 7 h (p<0.05). This difference was observed in premenopausal and postmenopausal women (p<0.05 for each). The association seen in women appears to be non-linear (p=0.02), but not in men (p=0.09). No statistically significant associations between sleep duration and fibrinogen or factor VII were seen.
Conclusions Men sleeping for both short and long periods had higher vWF levels than those who slept for 7 h. In women, there was a significant non-linear association with the highest levels mainly seen in long sleepers, irrespective of menopausal status. No major associations between sleep and either factor VII or fibrinogen were observed. Further longitudinal studies are required to fully investigate possible temporal relationships between sleep and vWF and the possible associated risk of CVD.