L-tryptophan: effects on daytime sleep latency and the waking EEG.

The effects of L-tryptophan (4 g) on the waking EEG and daytime sleep were studied in a group of 20 normal adults. Subjects were assigned to a morning or afternoon group, and data were collected on two occasions, after L-tryptophan and after placebo, assigned in a counterbalanced order. L-Tryptophan significantly reduced sleep latency without altering nap sleep stages and elevated plasma total and free tryptophan levels. EEGs were digitized on-line and later analyzed for changes in 5 frequency bands: 16-40 c/sec (beta), 13.0-15.5 c/sec (sigma), 8.0-12.5 c/sec (alpha), 4.0-7.5 c/sec (theta) and 0.5-3.5 c/sec (delta). During waking EEGs, L-tryptophan significantly increased alpha time, theta time, and theta intensity and significantly decreased alpha frequency. No wave bands were altered during sleep. L-Tryptophan is an effective daytime hypnotic which can facilitate sleep onset at clock times which do not coincide with biological sleep times. The hypnotic effects may be mediated by lowering arousal level during the awake state, thus setting the stage for more rapid sleep onset.

Norwegian military field exercises in the arctic: cognitive and physical performance.

In an effort to determine whether or not field living conditions degrade performance during cold weather military training, performance of 17 Norwegian Army soldiers living in tents in the field (FG) was compared with that of 13 soldiers living in barracks (GG). FG and GG performed similar tasks and were equipped and clothed identically. Each subject was tested prior to and following 9 days of field training. The tests consisted of marksmanship (score for a 5-shot group), snowshoe running (time to cover 1700 m), anaerobic power (Wingate test), and performance on 5 cognitive tests (preferred hand tapping, 4-choice reaction time, pattern recognition, memory search, and code substitution; each test scored as % correct and # completed). A subset of the subjects from each group wore watches which recorded heart rate during the day. During training GG had a lower average heart rate than FG, indicating lower physical activity level. Significant changes were not found in rifle shooting or in mean anaerobic power. Significant group (p less than .001) and time (p less than .001; pre vs. post) differences were found in snowshoe time, but a significant interaction was not found. Among the cognitive tests, a significant group by time interaction was found for % correct responses only for the Memory Search task, and represented a decrease in GG performance while FG performance was maintained. Time differences were found for # completed for Memory Search (p less than .002) and Pattern Recognition (p less than .001) suggesting incomplete learning of the task, but no group by time interactions were found.(ABSTRACT TRUNCATED AT 250 WORDS)