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.