Abstract
BackgroundThe association between lower serum sodium levels and the clinical outcomes of insomnia patients remains unclear. We explored whether lower serum sodium is associated with poor clinical outcomes in patients with insomnia.MethodsWe retrospectively enrolled patients with a diagnosis of insomnia from January 2011 to December 2012. We divided participants into three groups according to initial serum sodium level: tertile 1 (< 138 mmol/L), tertile 2 (138.0–140.9 mmol/L), and tertile 3 (≥ 141.0 mmol/L). To calculate the relative risk of death, hazard ratios (HRs) and 95% confidence intervals (CIs) were obtained using Cox proportional hazard models.ResultsA total of 412 patients with insomnia were included, of whom 13.6% (n = 56) had hyponatremia. Patients with lower serum sodium concentrations were older and had lower hemoglobin, calcium, phosphorus, and albumin levels. At the median follow-up of 49.4 months, 44 patients had died and 62 experienced acute kidney injury (AKI). Kaplan-Meier analysis showed significantly higher mortality in patients in the lowest tertile for serum sodium. The lowest tertile of the serum sodium level and the AKI were associated with all-cause mortality. However, the lowest tertile of the serum sodium level was not significantly associated with AKI.ConclusionsThe lowest tertile of the serum sodium level was associated with a higher mortality rate in insomnia patients. Our results suggest that the serum sodium level could serve as a prognostic factor in insomniacs; patients with lower sodium levels require particular care.
Highlights
The association between lower serum sodium levels and the clinical outcomes of insomnia patients remains unclear
Our study showed a U-shaped relationship between overall serum sodium level and mortality and the lowest tertile of serum sodium was significantly associated with increased all-cause mortality even after adjusting for covariates
We found that the heart rate (HR) was related to sympathetic nerve activity, but there was no significant association of the HR with the serum sodium level or mortality
Summary
The association between lower serum sodium levels and the clinical outcomes of insomnia patients remains unclear. We explored whether lower serum sodium is associated with poor clinical outcomes in patients with insomnia. Insomnia is a disorder characterized by at least one “nocturnal sleep symptom” and a daytime or “waking symptom” attributable to poor sleep [1]. Sodium is the main contributor to plasma osmolarity; certain disorders are typically characterized by hyponatremia and hypernatremia. Recent studies have shown that mild hyponatremia is associated with attention deficit, gait disturbance, and falls in patients admitted to the emergency room [9, 10]. Even mild hyponatremia is believed to be associated with risk of fracture [11] and mortality in adults living in the community [12,13,14]
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