SAN DIEGO – Shorter sleep duration is prospectively and independently associated with a faster decline in renal function, according to results from a large observational study.
“We know that people with chronic kidney disease have a disrupted sleep pattern, particularly those on dialysis,” lead study author Dr. Ciaran Joseph McMullan said in an interview in advance of Kidney Week 2015.
Dr. Ciaran Joseph McMullan
“Disrupted sleep is actually one of the symptoms of end-stage renal disease,” Dr. McMullan noted, “but what hasn’t been studied as much is when the sleep disturbances occur in the progression from normal kidney function to chronic kidney disease and further on to end-stage renal disease. It’s unclear at what point those abnormal sleep patterns develop.”
Medical research in the past decade has demonstrated that disrupting people’s sleep can affect their metabolism in profound ways, explained Dr. McMullan of the renal division at Brigham and Women’s Hospital, Boston.
“You can take healthy people, reduce their sleep each night to around 5 hours, and they can develop characteristics of diabetes,” he said. “In the long term, we know that people who sleep less are at increased risk of developing hypertension, an increased risk of developing diabetes, and an increased mortality overall. Two of the most important risk factors for kidney disease are diabetes and hypertension.”
For the current study, Dr. McMullan and his associates prospectively evaluated 4,238 participants from the Nurses’ Health Study who had their renal function measured on at least two occasions and had their sleep function reported in a 24-hour period between 1989 and 2000.
Sleep duration was based on self-report and included four categories: 5 hours or fewer per night, 6 hours per night, 7-8 hours per night, and 9 or more hours per night. Rapid decline in renal function was defined as a decline of estimated glomerular filtration rate (eGFR) of 25% or more over the 11-year period.
The researchers found that, compared with sleeping 7-8 hours per night, the adjusted odds ratios for a rapid decline in renal function were 1.65 for sleeping 5 or fewer hours per night, 1.31 for sleeping 6 hours per night, and 0.78 for sleeping 9 or more hours per night.
At the same time, the adjusted annualized decline in eGFR was 1.2 mL/min per 1.73 m2 per year among those sleeping 5 or fewer hours per night, 0.9 mL/ per 1.73 m2 per year among those sleeping 6 hours per night, and 0.8 mL/ per 1.73 m2 per year among those sleeping 7-8 hours per night, as well as those sleeping 9 or more hours per night (P = .02 for trend).
“This is the first time that we’ve studied people longitudinally to see how their kidney function changes over time based on how much they sleep per night,” Dr. McMullan said.
While he acknowledged that the study is limited by its observational design, the findings “lead us to consider if normal kidney function is disrupted by short sleep that may cause an irreversible decline in kidney function over time.
“I think we need to repeat this study using more accurate measurements of sleep, [such as] polysomnography to measure sleep duration and quality of sleep more accurately,” he said. “This would help us answer the question, ‘Why do these individual with short sleep duration have a more rapid decline of their kidney function?’ ”
Dr. McMullan added that “we also don’t know if lengthening sleep duration in individuals who have habitual sleep restriction is beneficial for their kidney function. This would be important to know before we can make any kind of clinical recommendation.”
The study was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases. Dr. McMullan reported having no financial disclosures.