Does cumulative night-shift exposure show a dose-response relationship with arterial stiffness and vascular function?

What "dose-response" means for shift workers

A dose-response relationship means the harm scales with the exposure: the more night shifts someone has worked, the more their blood vessels show the change. In vascular terms, the key measure is arterial stiffness, how much the artery wall resists the pulse of blood pushing through it. Stiffer arteries are a recognized marker of vascular aging and cardiovascular risk.

Reviews of this literature report exactly that gradient. A systematic review of occupational and healthcare evidence found that cumulative night-shift exposure was associated with increased arterial stiffness [1]. A separate systematic review of shift work and early vascular aging likewise reported dose-response relationships with vascular outcomes, including pulse wave velocity (a standard stiffness measure) and carotid artery thickness [2]. In plain terms, longer exposure tracked with worse vessel measures.

The clearest worker-level signal comes from one industrial study

The most direct worker-level evidence is a cross-sectional study of 101 night-shift and day workers in industry. Workers rotated between day, evening, and night shifts over six years, and night-shift work was associated with increased arterial stiffness [3]. Because the study compared people at a single point in time, it can show that shift workers differ from day workers, but it cannot by itself prove that the shifts caused the difference.

That limitation matters for how strongly to read the dose-response claim. The reviews synthesize many studies and describe a gradient [1][2], but the underlying designs are largely observational. The pattern is consistent across sources, which strengthens it, yet consistency is not the same as proof of cause.

Why night work might affect the arteries

One proposed route is sleep. In a study of transportation noise, night-time noise events were associated with arterial stiffness measured by brachial-ankle pulse wave velocity, and the authors suggested this might work partly through sleep impairment [5]. Night shifts disrupt sleep in an analogous way, so disturbed sleep is a plausible pathway, though that study examined noise rather than shift schedules and does not establish the mechanism for shift work.

A second thread concerns oxidative stress and blood pressure regulation. A study of first responders examined antioxidant effects on endothelial function and blood pressure and referenced a dose-response relationship with shift-work years, including measurements the day after a night shift in night-shift nurses [4]. This is a possibility worth testing, not an established explanation, and its focus on cumulative night-shift exposure is not clearly defined.

How much confidence the current evidence supports

The honest reading is that the direction is fairly consistent but the strength is modest. Two systematic reviews converge on a dose-response association between shift work and vascular measures [1][2], and a small industrial study adds a concrete worker-level example [3]. None of these establishes the size of the effect, the exposure threshold at which it appears, or whether it reverses after leaving shift work.

The mechanistic studies are even more preliminary. The noise study supports a sleep-related pathway but for a different exposure [5], and the antioxidant study raises oxidative stress and blood pressure as candidates without pinning them to cumulative night shifts [4]. For a reader weighing this, the practical takeaway is that cumulative night-shift exposure is a credible vascular risk marker that deserves monitoring, while the precise dose-response curve and its causes remain open questions.

Sources used in this answer

Related research questions