Wellness Check: Sleep

Long sleep duration may be associated with carotid plaque burden

1. In this cross-sectional analysis, long sleep duration (≥9 hours) was significantly associated with carotid plaque presence and larger total plaque area.

2. However, short sleep duration and daytime sleepiness showed no association with carotid plaque burden.

Evidence Rating Level: 2 (Good)

Sleep is an essential part of cardiovascular health, as the American Heart Association outlines. Prior studies have indicated a relationship between sleep duration and stroke risk. However, the pathology behind this association has yet to be well studied. Therefore, the present study aimed to determine the association between sleep duration and subclinical carotid plaque burden — a precursor of stroke.

This cross-sectional analysis was part of the Northern Manhattan Study that enlisted a cohort of 3,298 racially diverse participants between 1998 and 2001. To be included in the Northern Manhattan Study, participants had to be 39 years or older, have no history of stroke, and have been residing in Manhattan for three or more months. The cross-sectional analysis was conducted on the 1553 participants with data available regarding carotid intima-media thickness, plaque presence, total plaque area, sleep duration, and daytime sleepiness. A carotid ultrasound was performed to determine carotid plaque burden, and information on sleep duration and daytime sleepiness were determined through annual questionnaires from 2004 to 2011. Participants were divided into groups based on sleep duration as either short (<7 hours), intermediate (≥ 7 and <9 hours), or long (≥9 hours). The primary outcome was the association between sleep duration and carotid plaque burden.

The results demonstrated that long sleep duration was significantly associated with carotid plaque presence and larger total plaque area. Meanwhile, short sleep duration and daytime sleepiness were not associated with plaque presence or total plaque area. Despite these findings, the study was limited by its cross-sectional nature, which prevented the analysis of causality between sleep duration and carotid plaque burden. Nonetheless, the study demonstrated that long sleep duration may affect a person’s carotid plaque burden.

Short sleep duration may be associated with the presence of dental caries

1. In this cross-sectional study, there was a negative association between sleep duration and dental caries.

2. Furthermore, those who slept an average of ≥7 hours were less likely to have dental caries than those who slept <7 hours.

Evidence Rating Level: 2 (Good)

Dental caries are highly prevalent worldwide and can significantly impact overall health and quality of life in patients. A lack of sleep can be associated with inflammation, reduced immune function, and increased susceptibility to many conditions. Although prior studies have hypothesized that sleep duration may be related to dental caries, these studies have primarily focused on pediatric populations. Thus, the present study aimed to understand the association between sleep duration and the risk of dental caries.

The cross-sectional study enlisted survey data from 5,205 American participants from the National Health and Nutritional Examination Survey (NHANES) database from 2018 to 2018. Participants were excluded if they were under the age of 16 or if they had incomplete dental examination or sleep questionnaire data. Information on dental caries, sleep duration, and demographics were extracted from already-available survey data. Statistical analyses were performed using Chi-squared tests and Poisson and Logistic regression analyses. The primary outcome was the association between sleep duration and the presence of dental caries.

The results demonstrated a significant negative association between sleep duration and dental caries. Those who slept an average of ≥7 hours were less likely to have dental caries than those who slept <7 hours. Furthermore, an additional hour of sleep was associated with reduced odds of experiencing dental caries. Despite these results, the study was limited by the self-reported nature of the sleep data, which may have introduced bias. Nonetheless, the study findings demonstrated that getting an adequate amount of sleep may have a positive impact on oral health outcomes.

Sleep extension is associated with improvements in athletic performance

1. In this systematic review, sleep extension was the most effective intervention for improving sleep and athletic performance in athletes.

2. However, napping demonstrated inconsistent results, with some studies indicating that napping had a positive effect on athletic performance, while others found no effect or a negative effect.

Evidence Rating Level: 1 (Excellent)

Sleep is essential for aiding in recovery for athletes. As a result, sleep disruptions are known to impact athletic performance negatively. Despite this, athletes often face sport-related and non-sport-related factors that may inhibit their ability to achieve optimal sleep. A prior study investigated the role of sleep interventions on athletic performance. Still, since this was published, several more studies have improved our understanding of the importance of sleep in athletes. Thus, the present aimed to provide an updated review of the impact of various sleep interventions on athletic performance amongst a wide selection of sports.

Of 1,584 identified records, 25 studies published between 2011 and 2021 were included in the review. Studies were included if they tested an intervention to improve sleep in athletes, measured a performance/recovery outcome, and reported on the relationship between sleep and athletic performance. Studies were excluded if they enlisted referees or military tactical athletes, only reported on subjective performance measures, or included sleep medications as an intervention. The review was performed using PRISMA guidelines. The risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials (RoB2). The primary outcome was the impact of various sleep interventions on recovery and athletic performance.

The results demonstrated that sleep extension was the most effective intervention for improving sleep and athletic performance. Light and mindfulness interventions also demonstrated an overall positive effect on performance. However, napping showed inconsistent results, with some studies indicating napping had a positive effect on athletic performance, while others found no effect or a negative effect. Napping did, however, positively impact some aspects of recovery, such as muscle damage and inflammation. Despite these findings, the review was limited by the high heterogeneity of the included studies, which may have impacted the results. Nonetheless, the present study demonstrated that longer sleep duration may positively affect athletic performance.

Image: PD

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