[Effects of weak low-frequency electromagnetic field on sleep structure during daytime sleep]. / Vliyanie ekspozitsii slabogo elektromagnitnogo polya sverkhnizkoi chastoty na strukturu dnevnogo sna.

OBJECTIVE: To test the hypothesis that weak electromagnetic fields of low frequencies (0.5-26 Hz) could affect daytime sleep features and structure. MATERIAL AND METHODS: Parameters of daytime sleep continuity were compared in the study with counterbalanced control/exposition (40 min exposure to electromagnetic field at 1 Hz/0.004 µT) scheme in 22 healthy volunteers. Nonlinear regression model was used to assess daytime sleep continuity. RESULTS: Exposure to a weak electromagnetic field of ultra-low frequency significantly improved the quality of sleep, assessed by the indicator of sleep continuity, namely, there were fewer transitions from the second and deeper stages of sleep to the first stage and to the state of wakefulness (p<0.0001). CONCLUSION: The results can be used to develop non-pharmacological methods of sleep correction, as well as to improve the quality of short-term sleep and its positive effect on well-being, cognitive function and working capacity.

[Application of the method of one-day learning in a Morris water maze to analyse the effects of sleep deprivation on memory trace recall 24 hours later, after learning].

The proposed model of a one-day spatial learning is of interest in research of how sleep influences the hippocamp-dependent memory consolidation. We have studied the influence of a one-day total sleep deprivation on spatial memory consolidation in hooded rats after a one-day learning in the Morris water maze according to Feldman et al. [2010] protocol. According to it rats had to find a submerged platform that was alternatively marked by a flag or completely invisible to an animal. In a previous study [Dorokhov et al., 2011] we have used another one-day learning protocol [Frick et al., 2000] and Wistar rats and have demonstrated a large interindividual variance in learning parameters and sleep deprivation effects on memory consolidation. In this study we confirm previously acquired results on negative impact of sleep deprivation on spatial memory consolidation. To demonstrate the effects of sleep deprivation on the results of one-day learning we are using for the first time an evaluation of the time spent by an animal in the area of the platform placement and corresponding areas in the other quadrants of the water maze.