Modafinil improves event related potentials P300 and contingent negative variation after 24 h sleep deprivation.

AIMS: The efficacy of modafinil as a countermeasure in the reduction of cognitive decline following 24 h of sleep deprivation (SD) on subjective sleepiness scales, event-related potential (ERP) P300, and contingent negative variation (CNV) was evaluated. MAIN METHODS: Eleven healthy males, age 25-30 years participated. The experiment was performed in five sessions on different days between 7 and 8a.m. Session 1, baseline recordings; Session 2, after one night's SD; Session 3, 48 h of recovery from SD; Session 4, after 1 week of Session 1, following one night's SD along with modafinil (400mg/day); Session 5, 48 h of recovery after SD+modafinil. KEY FINDINGS: Subjective sleepiness scores increased significantly after SD as compared to baseline (P<0.01), but remained unaltered after modafinil supplementation. There was an increase in N100 and P300 peak latencies of ERP following SD (P<0.01), which was reduced with modafinil (P<0.05). There was an increase in CNV M100 and P300 peak latencies after SD (P<0.01) which decreased with the use of modafinil (P<0.05). The CNV reaction time increased following SD (P<0.01) and decreased with the use of modafinil (P<0.05). No significant effects on ERP N200, P200 latencies and P200, P300 amplitudes and CNV N100, M200 peak latencies and M100, M200 amplitudes were observed. SIGNIFICANCE: The results strongly suggest that modafinil in a dose of 400mg/day, reduces the subjective sleepiness and cognitive decline following 24 h of SD.

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 4300 m 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.

Effect of L-carnitine supplementation on endurance exercise in normobaric/normoxic and hypobaric/hypoxic conditions.

OBJECTIVE: To evaluate the effect of L-carnitine supplementation on improving endurance exercise in normobaric/normoxic and hypobaric/hypoxic environments. METHODS: Six-week-endurance-trained male Sprague-Dawley rats (n = 24) were randomly divided into 2 groups: control and experimental; the latter group was supplemented with L-carnitine, administered orally in a dose of 100 mg x kg(-1) body weight. The animals were supplemented for 25 days under ambient normobaric/normoxic conditions and thereafter were exposed to 72 hours of hypobaric hypoxia equivalent to 6100 m. The supplementation was continued during the exposure. "Run to exhaustion" was recorded on day 1 (R1) (presupplementation) and on days 7 (R2), 14 (R3), 21 (R4), and 28 (R5, which followed the last 72 hours of hypoxic exposure) of supplementation. Food intake, body weight, and the biochemical measures of plasma glucose, total cholesterol, and high-density lipoprotein (HDL) cholesterol were recorded. RESULTS: There was a significant improvement in endurance exercise, as indicated by an increase in run to exhaustion following L-carnitine supplementation under normobaric normoxia (36%-39%) and hypobaric hypoxia (50%). L-carnitine supplementation had no effect on plasma glucose levels either at sea level or after hypoxic exposure. Total cholesterol was decreased in normoxic and HDL cholesterol was increased in normoxic and hypoxic conditions, indicating a beneficial effect of exercise. CONCLUSION: L-carnitine supplementation improved exercise endurance in rats exposed to normobaric normoxic and hypobaric hypoxic conditions. Such supplementation would be beneficial in delaying the onset of fatigue during prolonged exercise in both conditions, indicating its potentially beneficial use at high altitude.