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We conducted assessments of 28 children with impaired vision (VI group), with ages ranging from 12 to 17 years, and an equal number of age-matched, normal-sighted children (NS group). The VI group had significantly higher rates of breathing, heart rates, and diastolic blood pressure values compared to the NS group (Mann–Whitney U test). Twenty-four of the VI group formed pairs matched for age and degree of blindness, and we randomly assigned members of the pairs to two groups, viz., yoga and physical activity. Both groups spent an hour each day practicing yoga or working in the garden, depending on their group. After 3 weeks, the yoga group showed a significant decrease in breath rate (Wilcoxon paired signed ranks test). There was no change after the physical activity program. The results showed that children with visual impairment have higher physiological arousal than children with normal sight, with a marginal reduction in arousal following yoga.
Day time activities are known to influence the sleep on the following night. Cyclic meditation (CM) has recurring cycles. Previously, the low frequency (LF) power and the ratio between low frequency and high frequency (LF/HF ratio) of the heart rate variability (HRV) decreased during and after CM but not after a comparable period of supine rest (SR). In the present study, on thirty male volunteers, CM was practiced twice in the day and after this the HRV was recorded (1) while awake and (2) during 6 h of sleep (based on EEG, EMG and EGG recordings). This was similarly recorded for the night’s sleep following the day time practice of SR. Participants were randomly assigned to the two sessions and all of them practiced both CM and SR on different days. During the night following day time CM practice there were the following changes; a decrease in heart rate, LF power (n.u.), LF/HF ratio, and an increase in the number of pairs of Normal to Normal RR intervals differing by more than 50 ms divided by total number of all NN intervals (pNN50) (P < 0.05, in all cases, comparing sleep following CM compared with sleep following SR). No change was seen on the night following SR. Hence yoga practice during the day appears to shift sympatho-vagal balance in favor of parasympathetic dominance during sleep on the following night.