Analysis two types of K complexes on the human EEG based on classical continuous wavelet transform.

In our work, we compare EEG time-frequency features for two types of K-complexes detected in volunteers performing the monotonous psychomotor test with their eyes closed. Type I K-complexes preceded spontaneous awakenings, while after type II K-complexes, subjects continued to sleep at least for 10 s after. The total number of K-complexes in the group of 18 volunteers was 646, of which of which type I K-complexes was 150 and type II K-complexes was 496. Time-frequency analysis was performed using continuous wavelet transform. EEG wavelet spectral power was averaged upon several brain zones for each of the classical frequency ranges (slow wave, δ, θ, α, ß1, ß2, γ bands). The low-frequency oscillatory activity ( δ-band) preceding type I K-complexes was asymmetrical and most prominent in the left hemisphere. Statistically significant differences were obtained by averaging over the left and right hemispheres, as well as projections of the motor area of the brain, p<0.05. The maximal differences between the types I and II of K-complexes were demonstrated in δ-, θ-bands in the occipital and posterior temporal regions. The high amplitude of the motor cortex projection response in ß2-band, [20;30] Hz, related to the sensory-motor modality of task in monotonous psychomotor test. The δ-oscillatory activity preceding type I K-complexes was asymmetrical and most prominent in the left hemisphere may be due to the important role of the left hemisphere in spontaneous awakening from sleep during monotonous work, which is an interesting issue for future research.

[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.

[Associations between chronotype, road accidents and polymorphisms in genes linked with biological clock and dopaminergic system]. / Assotsiatsii khronotipa, avariinosti i polimorfizmov genov, sviazannykh s biologicheskimi chasami i dofaminergicheskoi sistemoi.

Public transport driving is a highly demanding activity requiring high skills and responsibility. Shift work, problems with regular sleep schedule negatively impact psychomotor reactions, cognitive functions and ability to react appropriately to the changing environment. For professional drivers all these factors may lead to the increased risk of a road accident. Individual differences in chronotype, cognitive and emotional control are partially genetically determined. AIM: Our study aimed to investigate the possible associations between chronotype parameters, traffic accident history and single nucleotide polymorphisms (SNPs) in a number of genes: RORA (rs1159814), CLOCK (rs12649507), PER3 (rs2640909), NPSR1 (rs324981), NPAS2 (rs4851377), DRD3 (rs6280), SLC6A3 (rs6347), DBH (rs1611125). MATERIAL AND METHODS: We have studied 303 professional bus drivers working on rolling shifts in the Moscow region who had a recorded history of road accidents. The studied group was genotyped on selected SNPs and has filled out two chronotype questionnaires: MCTQ and shortened SWPAQ (Putilov A.A, 2014). RESULTS: A mixed chronotype with high levels of morning and evening alertness prevailed in the group. A prominent social jetlag caused by shift work was found. For SNP in PER3 gene there was an association with morning activation. SNP in CLOCK gene was associated with social jetlag and the risk to cause a crash. Minor alleles of SNPs in NPSR1and SLC6A3 correlated with later chronotype and increased risk of a road accident. We suppose that these polymorphisms may be amongst the genetic factors connecting chronotype and road accident risk.

[Polymorphisms in Sleep and Cognitive Function Related Genes are Associated with Vehicle Crash History in Shift Working Bus Drivers].

Bus driving is a highly responsible profession. It requires constant engagement of attention and cog- nitive resources as well as vigilance and resistance to disruption of sleep- rhythms. There is ongoing research of genetic correlates of these individual characteristics. The aim of this study is to search for possible connections between single nucleotide polymorphisms and the history of road traffic accidents in professional bus driving. 299 professional drives working on rolling shifts with recorded history of traffic accidents took part in the study. Polymorphisms in circadian rhythm-, cognitive and emotional function-related genes were genotyped: CLOCK (rs 12649507), RORA (rs1159814), NPAS2 (rs4851377), NPSR1 (rs324981), PER3 (rs2640909), DRD3 (rs6280), SLC6A3 (rs6347), DBH(rs1611125). Significant associations for polymorphisms in CLOCK, NPSR1 and SLC6A3 with traffic crash parameters were found. We suppose that they are mediated by the difference in chronotype and sleep deprivation resistance for CLOCKand cognitive and emotional control for NPSRI and SLC6A3 polymorphisms.