The association between serum lipid metabolism and nightmares: insights from Mendelian randomization analysis of two samples.

Background: nightmares are a common sleep disorder characterized by distressing dreams, leading to sleep disruption and psychological distress. Emerging evidence suggests a potential link between lipid metabolism and nightmare occurrence, but the causal relationship is poorly understood. Objective: to investigate the causal relationship between blood lipid metabolism characteristics and the risk of nightmares using Mendelian randomization (MR) analysis. Methods: a two-sample Mendelian randomization (MR) analysis was conducted using data from genome-wide association studies (GWAS). The analysis focused on specific lipid metabolism traits, including triglyceride levels in HDL and LDL, the triglycerides to total lipids ratio in medium HDL, and the free cholesterol to total lipids ratio in medium LDL. The inverse variance weighting (IVW) method was used as the primary analytical approach, with supplementary analyses conducted using MR-Egger, weighted median, and weighted mode methods. Results: the study identified that higher triglyceride levels in HDL (OR = 0.40, 95 % CI: 0.16-0.98, p = 0.04) and LDL (OR = 0.24, 95 % CI: 0.10-0.57, p = 0.001), as well as a higher triglycerides to total lipids ratio in medium HDL (OR = 0.38, 95 % CI: 0.15-0.95, p = 0.04), were protective against the occurrence of nightmares. In contrast, a higher free cholesterol to total lipids ratio in medium LDL was associated with an increased risk of nightmares (OR = 3.14, 95 % CI: 1.29-7.67, p = 0.01). Conclusion: lipid metabolism characteristics have a causal relationship with nightmare risk. Proper regulation of lipid metabolism may help reduce nightmare prevalence, particularly in vulnerable populations. Further studies are needed to validate these findings and explore underlying mechanisms.