A low n-6/n-3 PUFA ratio and high level of dietary ɑ-linolenic acid improves sleep behavior in mice with insomnia

Camelina sativa oil (CSO) and Semen Ziziphi Spinosae oil (SZSO) are functional oils that have beneficial effects on brain health. This study evaluated the sedative and hypnotic effects of vegetable oils with various n − 6/n − 3 polyunsaturated fatty acids (PUFA) ratios and ɑ-linolenic acid (ALA) contents to mice. The n − 6/n − 3 PUFA ratios of CSO (CSO:SZSO = 1:0, 1.8 g/kg), SZSO (CSO:SZSO = 0:1, 1.8 g/kg), CSO-SZSO-L (CSO:SZSO = 1:1, 1.8 g/kg), and CSO-SZSO-H (CSO:SZSO = 1:1, 3.6 g/kg) were 0.51, 140, 1.69, and 1.69, respectively. The doses of ALA administered to mice with p-chlorophenylalanine-induced insomnia were approximately 0.64, 50 × 10^–4, 0.32, and 0.64 g/kg, respectively. The mice were administered CSO, SZSO, and a low-dose combination of CSO and SZSO for seven days with no obvious hypnotic effects. However, the administration of a high-dose combination of CSO and SZSO significantly prolonged sleep duration in mice with induced insomnia and inhibited the serum levels of corticotropin-releasing hormone, adrenocorticotropic hormone, and cortisol. Interestingly, there were no significant effects on the structure and function of the hippocampal tissue. The results indicated that the anti-insomnia effects of these vegetable oils were positively correlated with a low n − 6/n − 3 PUFA ratio and the absolute amount of ALA.