Acute effects of the very low carbohydrate diet on sleep indices
Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, Sydney, New South Wales, Australia. Nutritional Neuroscience
(Impact Factor: 2.27).
09/2008; 11(4):146-54. DOI: 10.1179/147683008X301540
We compared the effect of short-term consumption of a very low carbohydrate (VLC) diet over 48 h to a control mixed diet on sleep indices in healthy, non-obese men.
This study employed a repeated-measure design where subjects were given isocaloric (2400 kcal) diets and matching evening test meals (4 h before usual bed-time), which were either mixed low-fat, high carbohydrate (15.5%, 12.5% and 72% of energy from protein, fat and carbohydrate, respectively) or VLC (38%, 61% and < 1% of energy from protein, fat and carbohydrate, respectively). Polysomnographic testing was performed on the familiarization and control night, 4 h after the first VLC test meal (acute phase) and 48 h (ketosis phase) following commencement of the VLC diet.
Fourteen healthy, non-obese men (aged 18-35 years; body mass index 23.4 +/- 1.9 kg/m(2)) who were good sleepers took part in the study.
Objective sleep was recorded using a computerized sleep system. Urine ketone level was monitored with reagent strips before the evening test meals and at bed-time on the control night, during the VLC acute and ketosis phases. Blood glucose level was measured with a glucometer before the evening test meal until 120 min following the meal. Hunger and fullness were assessed immediately after the meal until bed-time with Likert scales.
The proportion of rapid-eye movement (REM) sleep to total sleep time was significantly reduced at the VLC acute and VLC ketosis when compared to the control night (P = 0.006; n = 11 and P = 0.05; n = 14, respectively). The percentage of slow wave sleep (SWS) significantly increased for both the VLC acute (17.7 +/- 6.7) and ketosis (17.8 +/- 6.1) phases compared to control (13.9 +/- 6.3), P = 0.02 for both phases.
In healthy, good sleepers, the VLC diet over the short-term promotes increases in the percentage of SWS (deep sleep stage 4) and a reduction in the percentage of REM sleep ('dreaming' sleep) compared to the control mixed diet. The sleep changes may be linked to the metabolism of the fat content of the VLC diet.
Available from: Shona Halson
- "Afaghi and colleagues [54, 55] conducted two studies investigating carbohydrate ingestion before sleep in healthy men. In the first study, high or low glycemic index (GI) meals were given 4 h or 1 h before sleep . "
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ABSTRACT: Sleep has numerous important physiological and cognitive functions that may be particularly important to elite athletes. Recent evidence, as well as anecdotal information, suggests that athletes may experience a reduced quality and/or quantity of sleep. Sleep deprivation can have significant effects on athletic performance, especially submaximal, prolonged exercise. Compromised sleep may also influence learning, memory, cognition, pain perception, immunity and inflammation. Furthermore, changes in glucose metabolism and neuroendocrine function as a result of chronic, partial sleep deprivation may result in alterations in carbohydrate metabolism, appetite, food intake and protein synthesis. These factors can ultimately have a negative influence on an athlete's nutritional, metabolic and endocrine status and hence potentially reduce athletic performance. Research has identified a number of neurotransmitters associated with the sleep-wake cycle. These include serotonin, gamma-aminobutyric acid, orexin, melanin-concentrating hormone, cholinergic, galanin, noradrenaline, and histamine. Therefore, nutritional interventions that may act on these neurotransmitters in the brain may also influence sleep. Carbohydrate, tryptophan, valerian, melatonin and other nutritional interventions have been investigated as possible sleep inducers and represent promising potential interventions. In this review, the factors influencing sleep quality and quantity in athletic populations are examined and the potential impact of nutritional interventions is considered. While there is some research investigating the effects of nutritional interventions on sleep, future research may highlight the importance of nutritional and dietary interventions to enhance sleep.
Available from: Maria Pilar Terrón
- ". While the total amount of carbohydrates may influence the architecture of sleep, it does not affect the duration. However, the evidence on whether carbohydrates positively impact sleep quality is not completely consistent, since consuming carbohydrate meals with high or low glycaemic loads seems not to affect any polysomnographically determined sleep index . On the contrary, some components of the typical human diet, such as vitamin B12, improve alertness and concentration and reduce the daytime sleepiness phase . "
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ABSTRACT: Free radicals and oxidative stress have been recognized as important factors in the biology of aging and in many age-associated degenerative diseases. Antioxidant systems deteriorate during aging. It is, thus, considered that one way to reduce the rate of aging and the risk of chronic disease is to avoid the formation of free radicals and reduce oxidative stress by strengthening antioxidant defences. Phytochemicals present in fruits, vegetables, grains, and other foodstuffs have been linked to reducing the risk of major oxidative stress-induced diseases. Some dietary components of foods possess biological activities which influence circadian rhythms in humans. Chrononutrition studies have shown that not only the content of food, but also the time of ingestion contributes to the natural functioning of the circadian system. Dietary interventions with antioxidant-enriched foods taking into account the principles of chrononutrition are of particular interest for the elderly since they may help amplify the already powerful benefits of phytochemicals as natural instruments with which to prevent or delay the onset of common age-related diseases.
Available from: Katri Peuhkuri
- "In small children (n = 594), teenage girls (n = 126), and in a small study of 30 Greek women, a trend was observed toward longer sleep duration, with subjects consuming more energy from fat, whereas in other large studies with adolescents (n = 240) and adults (n = 459 and n = 2828), short sleep duration was correlated with increased fat intake [8,10–13,47,58]. Studies of high-fat, low-carbohydrate diets have not observed marked differences but only a remote trend on sleep duration, but also some influence on the relation of non-REM and REM sleep as described above   . "
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ABSTRACT: Sleep, much like eating, is an essential part of life. The mechanisms of sleep are only partially clear and are the subject of intense research. There is increasing evidence showing that sleep has an influence on dietary choices. Both cross-sectional and epidemiologic studies have demonstrated that those who sleep less are more likely to consume energy-rich foods (such as fats or refined carbohydrates), to consume fewer portions of vegetables, and to have more irregular meal patterns. In this narrative review, we pose the opposite question: can ingested food affect sleep? The purpose of this review is to discuss the evidence linking diet and sleep and to determine whether what we eat and what kind of nutrients we obtain from the food consumed before bedtime matter. In addition, scientific evidence behind traditional sleep-promoting foods such as milk and some herbal products is briefly described. These are reviewed using data from clinical trials, mostly in healthy subjects. In addition, we discuss the possible mechanisms behind these observations. Lastly, we summarize our findings that emerging evidence confirms a link between diet and sleep. Overall, foods impacting the availability of tryptophan, as well as the synthesis of serotonin and melatonin, may be the most helpful in promoting sleep. Although there are clear physiological connections behind these effects, the clinical relevance needs to be studied further.
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