Originally published by 2 Minute Medicine^® (view original article). Reused on AccessMedicine with permission.

Sleep surgery for obstructive sleep apnea may decrease blood pressure

1. In this systematic review and meta-analysis, surgeries for sleep apnea showed improvements in obstructive sleep apnea symptoms as well as blood pressure.

2. Furthermore, there were significant decreases in blood pressure in both eastern and western countries, with no significant differences between the two demographic groups.

Evidence Rating Level: 2 (Good)

Obstructive sleep apnea (OSA) can obstruct the airway during sleep and is associated with increased blood pressure (BP). Continuous positive airway pressure (CPAP) is an effective first-line treatment that can also reduce BP; however, in a selected patient group, surgical intervention is necessary for OSA treatment. Surgery type include uvulopalatopharnygoplasty, and maxillomandibular advancement. This study’s objective was to evaluate the effects of surgery for the treatment of OSA on BP reduction.

This systematic review and meta-analysis used a literature search of OSA, sleep surgery, and BP terms. The study was conducted under PRISMA guidelines. Studies were included based on age criteria, polysomnography confirmed OSA, having surgery for OSA, and pre- and post- BP monitoring. Case reports, letters to the editor, and abstracts were excluded. Quality assessment was done using the Newcastle-Ottawa Scale. 4041 records were screened, and 3226 articles were reviewed by abstract and title. 61 studies were incorporated in full-text review.

26 studies were included in the review and meta-analysis. 22 studies were case series studies, while the remainder were case-control and randomized controlled trial studies. Study results showed a significant reduction in objective (apnea-hypopnea index) and subjective (Epworth Sleepiness Scale) markers of sleep apnea after surgical intervention. Furthermore, there was an overall mean reduction in systolic BP (5.6 mHg) and diastolic BP (3.9 mmHg) after surgical intervention. There were no differences in mean changes to BP between studies completed in eastern versus western countries. Subgroup analysis showed greater BP changes with greater reduction in objective OSA measures post-surgery. However, this study was limited due to use of primarily case series studies and there was no comparison between those having surgery and a control group. Nonetheless, this study was the first meta-analysis of OSA surgery and its effect on BP reduction.

Altered carbohydrate and protein intake may affect sleep quality

1. In this systematic review, long-term increased carbohydrate intake improved rapid eye movement (REM) sleep, and higher protein diets had poor effects on sleep.

2. Furthermore, caloric restriction alongside higher protein diet had positive sleep effects for overweight and obese individuals.

Evidence Rating Level: 2 (Good)

Poor sleep quality is associated with significant health morbidity. It has been noted that sleep and nutrition have a bidirectional relationship. Macronutrient manipulation has been commonly applied among popular weight loss diets. This study’s goal was to characterize the literature surrounding macronutrient changes in an individual’s diet, and the effects this may have on quality of sleep.

The study was a systematic review completed under PRISMA guidelines that searched for articles with sleep and diet terms.. Inclusion criteria consisted of studies that delivered any macronutrient intervention, included human participants, and measured some form of subjective or objective sleep measure. Studies that were non-English, pediatric, or animal-based were excluded. The Cochrane Risk of Bias tool was applied to assess the quality of studies. 1909 records were identified, 1680 articles were subsequently screened, and 28 were eligible for full-text analysis.

17 articles were included in a thematic analysis. Three macronutrient manipulation types were identified in the study that include acute intervention (less than 24 hours), longer-term manipulation, and macronutrient changes with energy restriction. Seven studies showed that longer-term manipulation of carbohydrates negatively affect non-REM sleep, but positively improves REM sleep. Furthermore, protein intake at the recommended amount reduced wake episodes; however, increased intake showed increased restlessness and wake time. Interestingly, amongst obese and overweight individuals, high protein diets with energy restriction had a positive impact on sleep. Finally, three studies regarding lipid intake manipulation were inconclusive in their effect. In summary, this study was limited by the heterogeneity of the studies as there was a variety of diet comparators. In addition, macronutrient intake differs greatly based on bioavailability, gastric emptying, and nutrient metabolism within each macronutrient. Nonetheless, this study was significant in beginning to to elucidate the relationship between sleep and macronutrient alteration.

Sleep disorders are risk factors in the onset of depression

1. In this systematic review and meta-analysis, it was found that insomnia, hypersomnia, obstructive sleep apnea, and restless legs syndrome acted as risk factors for future depression.

2. Furthermore, both short sleep duration (less than 7 hours) and long sleep duration (more than 8 to 9 hours) had a significant risk for the incidence of depression.

Evidence Rating Level: 1 (Excellent)

Depressive disorders are chronic diseases that often are associated with sleep disorders such as insomnia. Insomnia has been well documented as a risk factor for future incidence of depression; however, there is limited research in other sleep disorders and sleep duration. This study looked at determining if there is a sequential relationship between sleep disorders, circadian disorders, and depression.

This systematic review and meta-analysis was performed under PRISMA guidelines. A literature search of sleep problem terms and depression terms was conducted, with no research participant type or time limitations. Eligible studies were included if they were longitudinal cohort studies, had a minimum 12-month follow-up, excluded participants with baseline depression, and provided outcome indicators. Risk of bias was assessed by the Newcastle-Ottawa scale. Studies which provided depression as a continuous variable, or were case-control or cross-sectional studies were excluded.

Of 12,461 identified records, 56 studies were included in the meta-analysis. Results demonstrated that in the context of a baseline sleep disorder, participants were at a higher risk of depression. Furthermore, the prevalence of insomnia increased with age, but this relationship was not found in depression. Interestingly, three studies used objective sleep measures such as wrist actigraphy and polysomnography to study sleep disorder. These studies found that long sleep duration was the only sleep problem with significant predictive value for future depression. However, one limitation of the systematic review and meta-analysis was that the onset of depression was the only primary outcome, considering that depression is dynamic amongst individuals. Depression may also be a risk factor for sleep disorders; therefore, reverse predictive association would better elucidate the sequential relationship. Nonetheless, this study was a comprehensive evaluation of sleep disorders and their potential as a risk factor for depression.

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