Sleep

Peer-Reviewed Scientific Articles​

Tissue regeneration: Impact of sleep on stem cell regenerative capacity

URL: https://www.ncbi.nlm.nih.gov/m/pubmed/30393021/
Journal: Life Sciences
Publication Date: 12/2018
Summary: The circadian rhythm orchestrates many cellular functions, such as cell division, cell migration, metabolism and numerous intracellular biological processes. The physiological changes during sleep are believed to promote a suitable microenvironment for stem cells to proliferate, migrate and differentiate. These effects are mediated either directly by circadian clock genes or indirectly via hormones and cytokines. Hormones, such as melatonin and cortisol, are secreted in response to neural optic signals and act in harmony to regulate many biological functions during sleep. Herein, we correlate the effects of the main circadian genes on the expression of certain stem cell genes responsible for the regeneration of different tissues, including bone, cartilage, skin, and intestine. We also review the effects of different hormones and cytokines on stem cell activation or suppression and their relationship to the day/night cycle. The correlation of circadian rhythm with tissue regeneration could have implications in understanding the biology of sleep and tissue regeneration and in enhancing the efficacy and timing of surgical procedures.

Key Takeaways

The circadian rhythm is your natural biologic clock that regulates sleep and wakefullness. This clock also regulates cellular processes associated with metabolism, cell growth, and cell repair. One process regulated by this biological clock is tissue regeneration and stem cell activation. Following an appropriate sleep cycle can be helpful in tissue repair including recovery from surgeries.

The Neuroprotective Aspects of Sleep

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4651462/
Journal: MEDtube science
Publication Date: 11/2015
Summary: Sleep is an important component of human life, yet many people do not understand the relationship between the brain and the process of sleeping. Sleep has been proven to improve memory recall, regulate metabolism, and reduce mental fatigue. A minimum of 7 hours of daily sleep seems to be necessary for proper cognitive and behavioral function. The emotional and mental handicaps associated with chronic sleep loss as well as the highly hazardous situations which can be contributed to the lack of sleep is a serious concern that people need to be aware of. When one sleeps, the brain reorganizes and recharges itself, and removes toxic waste byproducts which have accumulated throughout the day. This evidence demonstrates that sleeping can clear the brain and help maintain its normal functioning. Multiple studies have been done to determine the effects of total sleep deprivation; more recently some have been conducted to show the effects of sleep restriction, which is a much more common occurrence, have the same effects as total sleep deprivation. Each phase of the sleep cycle restores and rejuvenates the brain for optimal function. When sleep is deprived, the active process of the glymphatic system does not have time to perform that function, so toxins can build up, and the effects will become apparent in cognitive abilities, behavior, and judgment. As a background for this paper we have reviewed literature and research of sleep phases, effects of sleep deprivation, and the glymphatic system of the brain and its restorative effect during the sleep cycle.

Key Takeaways

Sleep provides the brain the ability to recharge, store memories, make connections, improve memory recall, clear toxins, and much more. Throughout the day your brain processes information, and in doing so produces waste products that are toxic to the brain and must be cleared. Thus, the brain has its own clean up system called the glymphatic system that works to remove toxic metabolites from the brain while you sleep. Therefore sleep deprivation can lead to a build up of these toxins and lead to detrimental effects in brain function, which can lead to impairment in cognitive function, judgement, behavior, reaction time, etc. Sleep truly is a restorative state not only for the body but also for the mind. The average person should strive for a minimum of 7 hours of sleep daily for optimal glymphatic activity.

Night workers have lower levels of antioxidant defenses and higher levels of oxidative stress damage when compared to day workers

URL: https://www.nature.com/articles/s41598-019-40989-6
Journal: Nature
Publication Date: 03/2019
Summary: The effects of circadian misalignment and work shift on oxidative stress profile of shift workers have not been explored in the literature. The present study aimed to evaluate the role of shift work (day and night) and social jetlag – a measure of circadian misalignment – with oxidative stress markers. A cross-sectional study was performed with 79 men (21–65 years old, 27.56 ± 4.0 kg/m2) who worked the night shift (n = 37) or daytime (n = 42). The analyzed variables included anthropometric measures and determination of systemic levels of markers of oxidative damage and antioxidant defense. Social jetlag was calculated by the absolute difference between the mean sleep point on working and rest days. The night group presented higher systemic values of thiobarbituric acid reactive substances and hydrogen peroxide, and lower levels of nitrite, total antioxidant capacity, and catalase and superoxide dismutase activities in relation to the day group. However, social jetlag was not associated with oxidative stress-related biomarkers analyzed in the night group. These results suggest that the night worker has higher levels of oxidative stress damage and lower levels of antioxidant defenses, while social jetlag was not a possible responsible factor for this condition.

Key Takeaways

Shift workers experience a disruption of their circadian rhythm due to the nature of their work. When comparing lab results of shift workers and normal daytime workers, the shift workers had higher levels of oxidative stress and lower levels of antioxidants. This suggests that the nature of shift work is more stressful to the body and impairs the the body's natural intrinsic defense mechanism, which can make you more susceptible to illness, infection, cancer, etc.

Sleep Deprivation and Oxidative Stress in Animal Models: A Systematic Review

URL: https://www.hindawi.com/journals/omcl/2015/234952/
Journal: Oxidative Medicine and Cellular Longevity
Publication Date: 04/2015
Summary: Because the function and mechanisms of sleep are partially clear, here we applied a meta-analysis to address the issue whether sleep function includes antioxidative properties in mice and rats. Given the expansion of the knowledge in the sleep field, it is indeed ambitious to describe all mammals, or other animals, in which sleep shows an antioxidant function. However, in this paper we reviewed the current understanding from basic studies in two species to drive the hypothesis that sleep is a dynamic-resting state with antioxidative properties. We performed a systematic review of articles cited in Medline, Scopus, and Web of Science until March 2015 using the following search terms: Sleep or sleep deprivation and oxidative stress, lipid peroxidation, glutathione, nitric oxide, catalase or superoxide dismutase. We found a total of 266 studies. After inclusion and exclusion criteria, 44 articles were included, which are presented and discussed in this study. The complex relationship between sleep duration and oxidative stress is discussed. Further studies should consider molecular and genetic approaches to determine whether disrupted sleep promotes oxidative stress.

Key Takeaways

Sleep deprivation promotes oxidative stress, however this review suggests that sleep deprivation is correlated with an increase in production of antioxidants as a protective mechanism. While the body may have a built in protective mechanism for sleep deprivation, one should be weary of the effects of chronic sleep deprivation.

Acute effects of the very low carbohydrate diet on sleep indices

URL: https://www.ncbi.nlm.nih.gov/m/pubmed/18681982/
Journal: Nutritional Neuroscience
Publication Date: 08/2008
Summary: 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.

Key Takeaways

Low Carb Ketogenic diets saw increases in slow wave sleep and decreases in REM sleep. REM sleep is generally thought to play a role in memory consolidation and learning, while slow wave sleep is thought to be responsible for physical restoration.

Later circadian timing of food intake is associated with increased body fat

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657289/
Journal: The American Journal of Clinical Nutrition
Publication Date: 11/2017
Summary: Nonlean individuals (high body fat) consumed most of their calories 1.1 h closer to melatonin onset, which heralds the beginning of the biological night, than did lean individuals (low body fat) (log-rank P = 0.009). In contrast, there were no differences between lean and nonlean individuals in the clock hour of food consumption (P = 0.72). Multiple regression analysis showed that the timing of food intake relative to melatonin onset was significantly associated with the percentage of body fat and body mass index (both P < 0.05) while controlling for sex, whereas no relations were found between the clock hour of food intake, caloric amount, meal macronutrient composition, activity or exercise level, or sleep duration and either of these body composition measures (all P > 0.72).

Key Takeaways

Eating your last meal later in the night is associated with higher levels of body fat.

Meal Timing Regulates the Human Circadian System

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5483233/
Journal: Current Biology
Publication Date: 06/2017
Summary: Circadian rhythms, metabolism, and nutrition are intimately linked [1, 2], although effects of meal timing on the human circadian system are poorly understood. We investigated the effect of a 5-hr delay in meals on markers of the human master clock and multiple peripheral circadian rhythms. Ten healthy young men undertook a 13-day laboratory protocol. Three meals (breakfast, lunch, dinner) were given at 5-hr intervals, beginning either 0.5 (early) or 5.5 (late) hr after wake. Participants were acclimated to early meals and then switched to late meals for 6 days. After each meal schedule, participants’ circadian rhythms were measured in a 37-hr constant routine that removes sleep and environmental rhythms while replacing meals with hourly isocaloric snacks. Meal timing did not alter actigraphic sleep parameters before circadian rhythm measurement. In constant routines, meal timing did not affect rhythms of subjective hunger and sleepiness, master clock markers (plasma melatonin and cortisol), plasma triglycerides, or clock gene expression in whole blood. Following late meals, however, plasma glucose rhythms were delayed by 5.69 ± 1.29 hr (p < 0.001), and average glucose concentration decreased by 0.27 ± 0.05 mM (p < 0.001). In adipose tissue, PER2 mRNA rhythms were delayed by 0.97 ± 0.29 hr (p < 0.01), indicating that human molecular clocks may be regulated by feeding time and could underpin plasma glucose changes. Timed meals therefore play a role in synchronizing peripheral circadian rhythms in humans and may have particular relevance for patients with circadian rhythm disorders, shift workers, and transmeridian travelers.

Key Takeaways

Meal timing does not seem to affect hunger, sleepiness, circadian clock markers, triglycerides, or clock gene expression, but eating later after waking up was shown to be correlated with lower plasma glucose and a delayed action of the PER2 gene, which allows for fat production.

Subjective sleep quality, unstimulated sexual arousal, and sexual frequency

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5760048/
Journal: Sleep science (São Paulo, Brazil)
Publication Date: 03/2019
Summary: Poorer sleep quality correlated with greater unstimulated sexual arousal in men with higher T levels and in women with higher T levels not taking oral contraceptives. In women with lower T, poorer subjective sleep quality correlated with greater sexual dissatisfaction. In both sexes, sleep quality was uncorrelated with sexual desire and sexual frequency over the past month.

Key Takeaways

Men and Women who do not take birth control will have more unstimulated sexual arousal if they did not get enough sleep and they have higher testosterone levels. However, lack of sleep did not lead to more sexual interactions. Additionally, women with lower Testosterone levels are less satisfied with sex.

Sex and Sleep: Perceptions of Sex as a Sleep Promoting Behavior in the General Adult Population

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6409294/
Journal: Frontiers in Public Health
Publication Date: 03/2019
Summary: Orgasms with a partner were associated with the perception of favorable sleep outcomes, however, orgasms achieved through masturbation (self-stimulation) were associated with the perception of better sleep quality and latency. These findings indicate that the public perceive sexual activity with orgasm precedes improved sleep outcomes. Promoting safe sexual activity before bed may offer a novel behavioral strategy for promoting sleep.

Key Takeaways

Orgasming before sleep leads to improvement in sleep quality. This effect was found with both masturbation and sexual intercourse with a partner, however sexual intercourse led to a greater improvement in sleep outcomes.

The bidirectional relationship between exercise and sleep: Implications for exercise adherence and sleep improvement

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4341978/
Journal: American Journal of Lifestyle Medicine
Publication Date: 11/2015
Summary: Exercise has long been associated with better sleep, and evidence is accumulating on the efficacy of exercise as a nonpharmacologic treatment option for disturbed sleep. Recent research, however, has noted that poor sleep may contribute to low physical activity levels, emphasizing a robust bidirectional relationship between exercise and sleep. This article will briefly review the evidence supporting the use of exercise as a nonpharmacologic treatment for sleep disturbance, outline future research that is needed to establish the viability of exercise as a behavioral sleep treatment, describe recent research that has emphasized the potential influence of poor sleep on daytime activity levels, and discuss whether improving sleep may facilitate adoption and/or better adherence to a physically active lifestyle. With poor sleep and physical inactivity each recognized as key public health priorities, additional research into the bidirectional relationship between exercise and sleep has significant implications for facilitating greater exercise adherence and improving sleep in society.

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