Night shift workers face a 15% higher risk of kidney stones, study warns
New research published in Mayo Clinic Proceedings and summarized by health reporters underscores a concerning health trend: working night shifts is linked to a 15% higher risk of developing kidney stones. The risk is not uniform across all night workers. Younger employees and those in sedentary jobs appear to be hit hardest. Experts say circadian rhythm disruption, combined with lifestyle factors like inadequate hydration, likely drives part of this increased risk.
What the study found
The large, long-running study tracked more than 220,000 adults over nearly 14 years, examining shift work schedules—how often people worked nights and for how long—and then comparing them with documented kidney stone events. The researchers reported a 15% elevation in risk among night-shift workers compared with daytime workers. Notably, the effect was strongest among younger workers and individuals whose jobs involved little physical activity. The findings also pointed to lifestyle correlates—smoking, poor sleep, low fluid intake, and higher body mass index (BMI)—as partial explanations for why nocturnal work may precipitate stone formation.
Why night shifts affect the kidneys
The body runs on a circadian rhythm, an internal 24-hour clock that coordinates sleep, digestion, hormone release, and metabolism. Night work means staying awake when the body expects rest and trying to sleep when it should be active, disrupting this clock. Lead investigator Yin Yang of Sun Yat-sen University notes that such disruption can alter how the body processes fluids and nutrients, influence hormone secretion, and encourage behaviors that favor stone development. In short, circadian misalignment not only causes fatigue but can tilt the body toward kidney stone formation by altering metabolism and hydration patterns.
In addition to clock disruption, several lifestyle factors common among night workers compound the risk. The study highlighted dehydration due to irregular hydration patterns, inconsistent meals, and reduced physical activity—a combination that can create an environment ripe for minerals to crystallize in the kidneys. These factors, together with sleep disturbances, form a syndemic effect that increases stone risk more than any single factor alone.
What exactly are kidney stones?
Kidney stones are mineral and salt deposits that form in the kidneys and can travel through the urinary tract. They range from sand-like grains to larger blocks that cause intense pain, painful urination, and sometimes blood in the urine. Stones are relatively common worldwide, with prevalence estimates varying by region, but they are far from rare in many adult populations. Importantly, stones can recur and have been linked to complications such as chronic kidney disease and, in rare cases, kidney failure. Recognizing symptoms early and seeking medical guidance can prevent complications and support timely treatment.
Practical steps to reduce the risk for night workers
Even if night shifts are unavoidable, there are concrete actions that can lower the chance of stone formation:
- Hydration: Aim for enough daily fluid intake to keep urine light-colored. A common target is about 2–3 liters per day, but individuals should adjust based on activity, climate, and medical advice.
- Smart eating: Limit high-sodium foods, processed snacks, and excess animal protein, all of which can raise stone risk. Favor fruits, vegetables, and whole grains, which support overall metabolic health.
- Regular physical activity: If the job is mostly sedentary, schedule movement before or after shifts, and incorporate short walks or quick workouts to support weight management and kidney health.
- Sleep quality: Create a dark, quiet sleep environment during the day, and try to maintain as consistent a sleep schedule as possible to reduce circadian stress.
- Medical checkups: If you have a history of stones or a family history, discuss preventive monitoring with your healthcare provider, including urine analysis and metabolic screening.
Advice for employers and health systems
Workplaces relying on night shifts, such as healthcare, transportation, and security sectors, should consider practical health-forward policies. Ensuring access to hydration stations, encouraging regular breaks for movement, and providing guidance on nutrition and sleep hygiene can help mitigate risk. Employee wellness programs that address hydration, nutrition, physical activity, and sleep are not just good for health—they also support productivity and safety in high-demand night environments.
Bottom line
The new study adds to a growing body of evidence that shift work can affect health beyond fatigue and mood. For younger night workers, the kidney stone risk is a real, actionable concern. While not everyone can swap shifts, adopting hydration strategies, smarter eating, and consistent movement can reduce risk and protect kidney health in the long term. Awareness is the first step, and proactive habits are the next.
