Plasma tryptophan and sheep

A Systematic Review, Meta-Analysis and Meta-Regression on the Effects of Carbohydrates on Sleep

This study aimed to assess the effects of quantity, quality and periodization of carbohydrates consumption on sleep. PubMed, SCOPUS and Cochrane Library were searched through October 2020. Data were pooled using random-effects meta-analysis. Eleven articles were included in the meta-analysis which consisted of 27 separate nutrition trials, resulting in 16 comparison data sets (sleep quantity n = 11; sleep quality n = 5). Compared to high carbohydrate (HCI), low carbohydrate intake (LCI) moderately increased duration and proportion of N3 sleep stage (ES = 0.37; 95% CI = 0.18, 0.56; p < 0.001 and ES = 0.51; 95% CI = 0.33, 0.69; p < 0.001, respectively). HCI prolonged rapid eye movement (REM) stage duration (ES = −0.38; 95% CI = 0.05, −8.05; p < 0.001) and proportion (ES = −0.46; 95% CI = −0.83, −0.01; p < 0.001), compared to LCI. The quality of carbohydrate intake did not affect sleep stages. Meta-regression showed that the effectiveness of carbohydrate quantity and quality in sleep onset latency was significantly explained by alterations of carbohydrate intake as a percentage of daily energy intake (R² = 25.87, p = 0.018) and alterations in the glycemic load (R² = 50.8, p = 0.048), respectively. Alterations in glycemic load partially explained the variance of the effectiveness of carbohydrate quality in sleep efficiency (R² = 89.2, p < 0.001) and wake after sleep onset (R² = 64.9, p = 0.018). Carbohydrate quantity was shown to affect sleep architecture, and especially N3 and REM sleep stages. Alterations in both quantity and quality of carbohydrate intake showed a significant effect on sleep initiation. Variations in carbohydrate quality significantly affected measures of sleep continuation. Further studies are needed to assess the effect of long-term carbohydrate interventions on sleep.

Sleepiness after glucose in narcolepsy

The issue of whether a high carbohydrate intake affects sleepiness and sleep variables has been studied in normals but not in patients suffering from narcolepsy, despite anecdotal evidence that sugars may facilitate sleepiness in this population. This study investigated whether the intake of 50 g glucose exacerbated sleepiness in narcolepsy subjects. A double-blind cross-over study, involving 12 narcolepsy subjects and 12 matched controls, measured behaviour after a light lunch supplemented with a drink of either 50 g glucose or placebo (artificially sweetened drink). The main dependent variables were the performance and EEG measures from the Wilkinson Auditory Vigilance Task (WAVT) and sleep variables from a 45 minute nap. The results indicate that in the narcolepsy subjects glucose was associated with decreased wake duration, reduced sleep onset latency and more spontaneous and induced sleep stage changes during the WAVT, while the nap revealed an increased intensity of sleepiness after glucose as measured by the Polygraphic Score of Sleepiness. Eleven of the twelve narcolepsy subjects showed increased REM duration in the nap after glucose. The findings are discussed in relation to serotonin synthesis, basal sleepiness and possible irregularities in the action of insulin.

Sleep, activity, nutrition and mood

For the past fifteen years we have been studying aspects of relationships between sleep, activity, nutrition and mood. This paper comprises a brief statement of some of this research and our views to date.

L-tryptophan and sleep in healthy man

The effect of L-tryptophan on night-time and day-time sleep (from 14.00 h) sleep was studied in six healthy males aged between 20 and 30 years. The doses used in the night-time studies were 2, 4 and 6 g, and in the day-time studies 1, 2 and 4 g. It was not possible to establish an effect of L-tryptophan compared with placebo on night-time sleep, but analysis of the sleep measures with 4 g compared with placebo and the other doses of L-tryptophan considered together suggested reduced awakenings, increased stage 3 and an increased percentage of REM sleep. With 4 g L-tryptophan there was an increase in the duration of stage 3 of day-time sleep compared with placebo. The studies provide marginal evidence that REM sleep may be modified by L-tryptophan in man, though the evidence is somewhat stronger that SWS may be increased. The effect on REM sleep may involve circadian mechanisms. The hypnotic activity of L-tryptophan per se is limited and uncertain.

Behavioral alteration of plasma phenylalanine concentration

The concentration of 13 neutral and acidic plasma amino acids was measured before, during and after either 40 min of control relaxation or 40 min of the process known as transcendental meditation (TM). An electro-oculogram, electroencephalogram, and electromyogram were simultaneously monitored in these subjects. Increased phenylalanine concentration was noted during TM practice with no change during control relaxation; no difference between the groups of total time slept or sleep stage percent was observed. The stability of phenylalanine concentration in controls and lack of correlation of increased phenylalanine with sleep in the long-term practitioners seem to suggest a relationship of the phenylalanine increase to TM practice.

Early morning migraine. Nocturnal plasma levels of catecholamines, tryptophan, glucose, and free fatty acids and sleep encephalographs

Nocturnal plasma catecholamine, tryptophan, glucose, and free fatty acid levels have been measured in 19 subjects who regularly awoke from sleep with migraine. All-night polygraphic sleep recordings were also made. 13 subjects were studied on a second occasion allowing within-subject control as well as group comparison. Plasma total catecholamine and specifically plasma-noradrenaline levels were significantly higher in the three hours before the subjects awoke with migraine. No differences were found in plasma tryptophan, glucose, insulin, and free fatty acid levels in the migraine/no-migraine categories. Waking with migraine occurred significantly more often from rapid-eye movement (REM) sleep. There were no other differences in sleep pattern in the migraine/no-migraine categories.

5-Hydroxytryptamine (5-HT) in the whole-blood of patients with depressive illness

Whole-blood 5-HT was examined in thirty-five depressive patients not on antidepressants, and in comparable control subjects. The concentration of whole-blood 5-HT was significantly lower during depression, but returned to normal after clinical recovery.

Isocaloric diet changes and electroencephalographic sleep

Electroencephalographic (E.E.G.) sleep changes were studied in eight young healthy male subjects who were given a normal balanced diet or a high-carbohydrate/low-fat or low-carbohydrate/high-fat isocaloric diet, according to an experimental design. Significantly less slow-wave sleep (S.W.S.) was found after consuming a high-carbohydrate/low-fat diet than after consuming a normal balanced diet or a low-carbohydrate/high-fat diet. The latter two diets did not differ in terms of the amounts of S.W.S. Both high-carbohydrate/low-fat and low-carbohydrate/high-fat isocaloric diets, especially the former, were associated with significantly more rapid-eye-movement (R.E.M.) sleep than was the normal balanced diet. These findings emphasise the importance of daily diet for the following night's sleep.