Meditation as an intervention for cognitive disturbances following total sleep deprivation.

Background & objectives: Decline in cognitive functions is a major challenge for professionals during sustained wakefulness. We used middle latency response (MLR), event related potentials P300-ERP and contingent negative variation (CNV) and Raven’s Advanced Progressive Matrices (RAPM) - a standard neuropsychological test were used to evaluate cognitive impairment after total sleep deprivation (SD); and to study the impact of meditation as an intervention for this impairment. Methods: Healthy male volunteers (n=10) drawn randomly from the Indian Army participated in a 6-night study design executed before and after two months of meditation practice: night 1–adaptation, night 2–baseline, night 3–24 h SD, night 4–recovery sleep, night 5–24 h SD after 60 days meditation, night 6–recovery sleep after SD. A 36 h SD was obtained by keeping the subject awake for 12 h after 24 h SD. Results: The latency and amplitude of P300 increased after 36 h SD. Amplitudes and latencies of both early and late CNV increased after 24 and 36 h SD, indicating deficient orientation and impairment of attention and perception. Prolonged CNV reaction time after 36 h SD manifested deficient motor response following second (imperative) stimulus. Latency of MLR Na registered significant change following 36 h SD compared to baseline (P<0.01) and recovery (P<0.05). RAPM score showed significant decrease after 36 h of wakefulness indicating impaired analytical ability and difficulty in problem solving. None of these parameters showed any significant alteration after SD, following meditation practice. Interpretation & conclusions: The present results showed that SD impaired cognitive performance to graded extents significantly, but this deterioration could be improved to a significant extent using meditation.

Sleep architecture at 4300 m altitude in a sample of Indian lowlanders.

The present study aimed to evaluate sleep architecture at 4300m in a sample of 10 healthy Indian lowlanders, mean age 25.7±5.1 yrs. Polysomnography on two consecutive nights each was performed at sea level and 4300 m, the first night for adaptation and the second one for actual recording. Total sleep time reduced from 433.33±8.95 to 412.06±13.13 minutes (P<0.0005), sleep latency increased from 11.56±6.85 to 22.22±7.95 minutes (P<0.0025), deep NREM sleep (S3+S4) reduced from 79.56±28.45 to 45.39±25.32 minutes (P<0.01), light NREM sleep (S1+S2) increased from 272.94±20.63 to 296.72±23.24 minutes (P<0.05), REM decreased from 80.89±7.65 to 69.94±11.30 minutes (P<0.02) and periodic breathing was present in 4 of 10 participants on the second night at 4300 m. Decreased sleep quality (P<0.0005) and increased sleep disturbances (P<0.0005) were reported in subjective ratings at high altitude. Changes in sleep architecture similar to but of a greater magnitude are present on the second night of staged induction to 4300 m, than reported at 3500 m in our earlier study.