Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society on the Recommended Amount of Sleep for a Healthy Adult: Methodology and Discussion
2015; American Academy of Sleep Medicine; Volume: 11; Issue: 08 Linguagem: Inglês
10.5664/jcsm.4950
ISSN1550-9397
AutoresNathaniel F. Watson, M. Safwan Badr, Gregory Belenky, Donald L. Bliwise, Orfeu M. Buxton, Daniel J. Buysse, David F. Dinges, James E. Gangwisch, Michael A. Grandner, Clete A. Kushida, Raman K. Malhotra, Jennifer L. Martin, Sanjay R. Patel, Stuart F. Quan, Esra Tasali,
Tópico(s)Sleep and Work-Related Fatigue
ResumoFree AccessPhysiologyJoint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society on the Recommended Amount of Sleep for a Healthy Adult: Methodology and Discussion Consensus Conference Panel:, Nathaniel F. Watson, MD, MSc, M. Safwan Badr, MD, Gregory Belenky, MD, Donald L. Bliwise, PhD, Orfeu M. Buxton, PhD, Daniel Buysse, MD, David F. Dinges, PhD, James Gangwisch, PhD, Michael A. Grandner, PhD, MSTR, CBSM, Clete Kushida, MD, PhD, Raman K. Malhotra, MD, Jennifer L. Martin, PhD, Sanjay R. Patel, MD, MSc, Stuart F. Quan, MD, Esra Tasali, MD Consensus Conference Panel: , Nathaniel F. Watson, MD, MSc Address correspondence to: Nathaniel F. Watson, MD, MSc; 2510 N. Frontage Road, Darien, IL 60561(630) 737-9700(630) 737-9790 E-mail Address: [email protected] University of Washington, Seattle, WA , M. Safwan Badr, MD Wayne State University, Detroit, MI , Gregory Belenky, MD Washington State University, Spokane, WA , Donald L. Bliwise, PhD Emory University, Atlanta, GA , Orfeu M. Buxton, PhD Pennsylvania State University, University Park, PA , Daniel Buysse, MD University of Pittsburgh, Pittsburgh, PA , David F. Dinges, PhD University of Pennsylvania, Philadelphia, PA , James Gangwisch, PhD Columbia University, New York, NY , Michael A. Grandner, PhD, MSTR, CBSM University of Pennsylvania, Philadelphia, PA , Clete Kushida, MD, PhD Stanford University, Stanford, CA , Raman K. Malhotra, MD Saint Louis University, St. Louis, MO , Jennifer L. Martin, PhD University of California, Los Angeles, Los Angeles, CA , Sanjay R. Patel, MD, MSc Harvard Medical School, Boston, MA , Stuart F. Quan, MD Harvard Medical School, Boston, MA , Esra Tasali, MD The University of Chicago, Chicago, IL Published Online:August 15, 2015https://doi.org/10.5664/jcsm.4950Cited by:186SectionsAbstractPDF ShareShare onFacebookTwitterLinkedInRedditEmail ToolsAdd to favoritesDownload CitationsTrack Citations AboutABSTRACTThe American Academy of Sleep Medicine and Sleep Research Society recently released a Consensus Statement regarding the recommended amount of sleep to promote optimal health in adults. This paper describes the methodology, background literature, voting process, and voting results for the consensus statement. In addition, we address important assumptions and challenges encountered during the consensus process. Finally, we outline future directions that will advance our understanding of sleep need and place sleep duration in the broader context of sleep health.Citation:Watson NF, Badr MS, Belenky G, Bliwise DL, Buxton OM, Buysse D, Dinges DF, Gangwisch J, Grandner MA, Kushida C, Malhotra RK, Martin JL, Patel SR, Quan SF, Tasali E. Joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society on the recommended amount of sleep for a healthy adult: methodology and discussion. J Clin Sleep Med 2015;11(8):931–952.1.0 INTRODUCTIONSleep is vital to human health, necessary for life,1,2 and it serves critical roles in brain functions including neurobehavioral, cognitive and safety-related performance,3–13 memory consolidation,14,15 mood regulation,16,17 nociception18,19 and clearance of brain metabolites.20,21 Sleep is also critically involved in systemic physiology, including metabolism,22–26 appetite regulation,27,28 immune and hormone function,29–33 and cardiovascular systems.34–37 Sleep duration is associated with mortality risk38–40 and with illnesses ranging from cardiovascular41 and cerebrovascular42 disease to obesity,43 diabetes,44 cancer,45,46 and depression.47These observations raise a critical question: How much sleep is needed for optimal health?Sleep duration shows substantial intra- and inter-individual variation. Twin studies show sleep duration heritability between 31% and 55%, suggesting substantial genetic influences on sleep need.23,48,49 Environmental factors, such as occupational duties and commute time, family responsibilities, and social and recreational opportunities, can lead to substantial discrepancies between the amount of sleep needed and the amount of sleep obtained.50 A recent Centers for Disease Control and Prevention (CDC) analysis shows that between 1985 and 2012 mean sleep duration decreased and the percentage of adults sleeping ≤ 6 hours in a 24-hour period increased. This trend represents a near doubling in the number of U.S. adults sleeping ≤ 6 hours in a 24-hour period from 38.6 million to 70.1 million.51 The CDC presently considers this progressive decline in sleep duration a public health epidemic.52In 2013, the American Academy of Sleep Medicine and Sleep Research Society received a one year grant, renewable annually for up to five years, from the CDC entitled the "National Healthy Sleep Awareness Project." This Project addresses the four sleep health objectives from Healthy People 2020,53 a U.S. Department of Health and Human Services initiative to improve the nation's health. Objective four is to "increase the proportion of adults who get sufficient sleep." In the course of stakeholder discussions on this objective it became evident that the fields of sleep research and sleep medicine lack a clear recommendation regarding what constitutes "sufficient" sleep. The absence of such guidance has wide ranging implications for personal and public health. Sleep restriction is the most common cause of sleepiness in society, yet clinicians struggle to tell their adult patients how much sleep is necessary to improve alertness. Public policy initiatives addressing operator fatigue and transportation safety are likewise hindered by the absence of evidence-based guidance regarding healthy habitual sleep duration in adults. The sleep medicine and research community stresses the importance of sleep for health, but this message is likewise undermined by the lack of consensus regarding healthy sleep duration in adults. The absence of such a consensus ultimately weakens the message that sleep is essential for health. Thus, clinical, public policy, and public health activities would all benefit from a consensus recommendation addressing the amount of sleep necessary to support optimal health and functioning in an adult.A panel of 15 experts in sleep medicine and sleep research used a modified RAND Appropriateness Method54 to develop an evidence based recommendation statement regarding the sleep duration that promotes optimal health in adults aged 18 to 60 years.55 Sleep duration is the subject of the recommendation statement, but other sleep measures also impact health. Sleep timing, self-reported sleep quality, day-to-day variability in sleep duration, napping, and sleep disorders all influence health outcomes in cross-sectional and/or longitudinal studies.56,57 At present, however, sleep duration is the most widely-studied, best-supported, and most straightforward sleep measure to address in relation to health. This supporting manuscript further describes the process, rationale, and discussion that resulted in this evidence-based sleep duration recommendation statement.2.0 METHODSThe American Academy of Sleep Medicine (AASM)/Sleep Research Society (SRS) Sleep Duration Consensus Conference used a modified RAND Appropriateness Method (RAM)54 to establish consensus for the amount of sleep needed to promote optimal health in adults.2.1 Expert Panel SelectionIn accordance with recommendations of the RAM, the Sleep Duration Consensus Conference panel comprised 15 members, including a moderator (who was also a member of both the Board of Directors of the American Academy of Sleep Medicine and the National Healthy Sleep Awareness Project Strategic Planning Group). All panel members are experts in sleep medicine and/or sleep science. The panel consisted of members of the AASM and/or the SRS who were recommended by the Board of Directors of these respective organizations.Panel members were sent a formal letter of invitation from the AASM and SRS, and were required to complete Conflict of Interest disclosures before being officially accepted. To avoid further conflicts, panel members were not permitted to participate in similar consensus activities by other organizations.2.2 Modified RAND Appropriateness MethodThe RAND Appropriateness Method uses a detailed search of the relevant scientific literature, followed by two rounds of anonymous voting, to determine consensus on the appropriateness of a recommendation. The first round of voting is completed without panel interaction to prevent panel members from influencing each other's votes. The second round of voting occurs after a panel discussion of the available evidence and round 1 voting results.In a modification to RAM, the Consensus Conference included a third round of voting, which considered all available evidence and the previous voting results, to establish a single recommendation for the amount of sleep needed to promote optimal health in adults. The third round also involved a discussion of the merits of recommending an optimal sleep duration range versus a simple threshold value. The final Consensus Recommendation Statement55 resulted from the third round of voting.The charge to the Consensus Conference panel was to determine a sleep duration recommendation for adults. Panel members voted on the appropriateness of one-hour increments ranging from 5 to 10 hours of sleep, and of < 5 and ≥ 10 hours of sleep. One hour increments were selected because these were the most commonly-reported units in epidemiologic and experimental studies. Substantial heterogeneity was present in sleep duration assessment instruments. For the sake of parsimony, the consensus recommendation focused on "nightly" sleep without specification of napping, as this conformed with the majority of assessments used in epidemiologic studies. The final recommendation was based on the one-hour values that were determined by the panel to be "appropriate" to promote optimal health in adults.2.3 Detailed Literature Search and ReviewThe AASM and SRS charged the panel with developing a recommendation for sleep duration in adults. This charge coincides with the goals of the National Healthy Sleep Awareness Project (NHSAP) and with a Sleep Health Objective of Healthy People 2020 to "increase the proportion of adults who get sufficient sleep."53After a preliminary review of the literature, the scope of the recommendation was limited to adults aged 18 to 60 years. The age cutoffs were based on a meta-analysis of sleep obtained by healthy individuals across the lifespan that showed children and adolescents have longer sleep times than adults, and older adults show no substantial age related declines in sleep duration after the age of 60.58 Epidemiological studies of a very large representative sample of Americans also supported the conclusion that adults aged 18 to 60 years had shorter sleep durations than those younger and older.50,59 Older adults are also more likely to suffer from medical disorders that could confound associations between sleep duration and health outcomes. Initially, the panel planned to evaluate the literature separately for those aged 18–45 and 46–60, but the substantial overlap of age ranges among published studies precluded such analyses.The panel also initially planned to evaluate sleep duration separately for men and women. As detailed below, gender-specific voting was conducted during round 1 voting in all categories for which gender-specific evidence was available. After round 1 voting, however, the gender-specific votes were collapsed after voting results demonstrated the evidence did not meaningfully suggest different sleep duration recommendations between genders.A preliminary search of the literature and specific National Library of Medicine Medical Subject Headings (MeSH) terms identified several health outcomes that were most commonly examined in relation to sleep duration. Based on this evidence, the panel decided to focus on the relationships between sleep duration and nine health categories: (1) general health; (2) cardiovascular health; (3) metabolic health; (4) mental health; (5) immunologic health; (6) human performance; (7) cancer; (8) pain; and (9) mortality.After establishing the health categories, a detailed literature search was performed in PubMed on October 28, 2014. The search terms used for the literature search are detailed in Appendix A. The search was restricted to studies in human adults, published in English, with no publication date limit. Case reports, editorials, commentaries, letters, and news articles were excluded from the search results. The initial search produced 5,314 publications. The search results were reviewed based on title and excluded a priori for the following reasons: focusing on sleep quality or fatigue instead of sleep duration; assessing sleep duration in specific illnesses or sleep disorders; experimentation involving total sleep deprivation; inclusion of subjects sleeping outside normal day/night sleep schedules; assessing sleep deprivation as a treatment (e.g., depression); focusing on medication effects on sleep duration; and inclusion of participants outside the age range of 18 to 60 years. Application of these restrictions resulted in 1,266 publications.The panel reviewed the abstracts of these remaining publications using the same criteria described above. Pearling was used to capture important publications that were not identified by the search. Accepted publications were graded for quality using Oxford criteria.60 Each panel member assigned to a particular heath category was asked to identify the five most informative studies based on study design and evidence quality. All accepted publications with an Oxford grade of I, II, or III were reviewed in detail and the data listed in Table 1 were extracted. Based on the data extraction, accepted studies were subdivided into the categories and subcategories listed in Table 2. The extraction sheet and full text of all accepted publications were made available to the panel members for review. A second PubMed literature search was performed immediately prior to the conference (on January 22, 2015) to collect any additional relevant studies. The final list included 311 publications for consideration by the panel (Appendix B).Table 1 Data extracted from Oxford Grade I, II, and III studies for evidence tables.Table 1 Data extracted from Oxford Grade I, II, and III studies for evidence tables.Table 2 Nine health categories and subcategories with indication if gender-specific recommendations were considered in round 1 voting.Table 2 Nine health categories and subcategories with indication if gender-specific recommendations were considered in round 1 voting.2.4 Round 1 VotingPrior to the conference, panel members reviewed the accepted publications and extraction sheets. Based on their review of this material and their clinical and research expertise, members voted to indicate their agreement with the following statement: "Based on the available evidence, [X] hours of sleep is associated with optimal health within the [X] subcategory in the [X] category." "Hours of Sleep" was categorized as < 5 hours, 5 to 6 hours, 6 to 7 hours, 7 to 8 hours, 8 to 9 hours, 9 to 10 hours, and ≥ 10 hours. The panel members voted using a 9-point Likert scale where 1 meant "strongly disagree", 9 meant "strongly agree", and 5 meant "neither agree nor disagree". Panel median values were placed into three broader categories with the following interpretations; 1–3 indicated disagreement with the statement, 4–6 indicated uncertainty, 7–9 indicated agreement with the statement.Panel members were instructed not to discuss the evidence or their votes with each other to ensure independence. Panel members' votes were collected and compiled to determine the median and distribution of votes. Individual results tables were created and distributed to members at the consensus conference, displaying the distribution of votes (anonymized), the member's vote, and the median vote. When relevant, subcategory results were collapsed to reveal overall category specific results (Figure 1A).Figure 1: Voting results.Panel members used the following sentence to generate their individual vote for Rounds 1 and 2 on each subcategory (when necessary), category and each hour range of sleep: "Based on the available evidence, [X] hours of sleep is associated with optimal health within the [X] subcategory in the [X] category." Choice options ranged from 1–9 with 1 = "Strongly Disagree," 5 = "Neither Agree nor Disagree," and 9 = "Strongly Agree." Round 1 voting (A) occurred without influence from other Panel members, Round 2 voting (B) occurred at the face-to-face meeting in Chicago after category content expert presentations and group discussion, final consensus statement voting (C) occurred after group discussion and review of the Round 2 voting results. Consensus statement voting involved panel members using the following modified sentence to generate their vote: "Based on the available evidence, [X] hours of sleep is associated with optimal adult health." In regards to color coding of the figure, if there was consensus among the panel that < 5 hours of sleep was not associated with, for example, cardiovascular health, the relevant area in Figure 1 would be colored red (e.g., the panel reached consensus that it feels the following statement is inappropriate: "Based on the available evidence, < 5 hours of sleep is associated with optimal health within the hypertension subcategory within the cardiovascular health category"). For expository purposes, subcategories were collapsed to provide overall category specific results. A vertical line was placed on the figures to denote the 7 hour mark.Download Figure2.5 Conference Proceedings and Round 2 VotingPrior to the conference, one panel member was selected to act as a category expert for each category. At the conference, members reviewed the results of Round 1 voting for a category and the category expert presented a review of the best available evidence for that category. Panel members then discussed the results of Round 1 voting, the accepted publications for the category, and any other relevant evidence. After discussions, panel members completed Round 2 voting for the category and subcategories (when relevant) following the same procedures from Round 1 voting. The conference proceeded in this manner for all categories.Based on the results of Round 1 voting and the conference discussions, and with the agreement of all panel members, some subcategories were collapsed or dropped for Round 2 voting. This decision was based on the availability and strength of evidence. This resulted in the following categories/subcategories for Round 2 voting: (1) general health, (2) cardiovascular health (subdivided into hypertension and cardiovascular disease), (3) metabolic health (subdivided into diabetes and obesity), (4) mental health (subdivided into mood and psychiatric health), (5) immunologic health, (6) human performance (subdivided into cognitive performance and driving performance), (7) breast cancer, (8) pain, and (9) mortality. As with Round 1, Round 2 voting results for subcategories were collapsed to reveal overall category specific results (Figure 1B).2.6 Round 3 Voting and Development of Recommendation StatementPanel members reviewed and discussed Round 2 voting results for all categories and the entire body of accepted publications in preparation for voting on a single recommendation statement. After discussions were concluded, panel members completed Round 3 voting for the single recommendation statement (Figure 1C), following the same procedures as Round 1 and Round 2 voting but using the following statement: "Based on the available evidence, [X] hours of sleep is associated with optimal adult health." Upon completion of Round 3 voting, the panel members reviewed the voting results and crafted the language of the recommendation statement. After all panel members approved the language of the final statement it was submitted to the AASM and SRS Boards of Directors for their endorsement.3.0 SUMMARY OF LITERATUREThe following sections succinctly summarize the key evidence considered by the panel in developing the recommendation statement while acknowledging that a complete review of the evidence is beyond the scope of this document.3.1 General HealthThe majority of studies in this category were large-scale cross-sectional studies, although there were also prospective cohort and sleep restriction studies, with sample sizes ranging from 30 (prospective cohort study) to 75,718 (cross-sectional study) individuals. Some of the studies evaluated the relationship between sleep duration and general health using health-related quality-of-life (HRQOL) measures. The associations of sleep duration with HRQOL and sleep health disparities were examined in 2,391 young adults (20–39 years) using cross-sectional data from the National Health and Nutrition Examination Survey 2005–2008 (NHANES).61 Young adults who slept < 7 hours were more likely to report poor general health and low overall physical, and mental HRQOL than those sleeping ≥ 7 hours. Other studies focused on the risk or presence of one or more specific diseases. Many but not all of the studies indicated that < 7 hours is associated with poorer general health (typically assessed by HRQOL measures) and increased risk or presence of disease compared to 7–8 hours of sleep. There is less evidence for an association of longer sleep duration and adverse health status, with only a few studies demonstrating an association of poorer general health or increased risk/presence of disease with ≥ 9 hours of sleep.3.2 Cardiovascular HealthThe panel reviewed numerous studies addressing the association between sleep duration and broadly-defined cardiovascular disease. Many studies specifically targeted the relationship between sleep duration and hypertension. Most were cohort or cross-sectional studies of community based populations, although some utilized a case-control study design. The number of participants ranged from less than 100 in the case-control studies to over 200,000 in some of the cohort studies. For studies focused on overall cardiovascular disease, the most common outcomes were coronary heart disease, stroke or a combination of both, adjudicated through medical records or central registries. Hypertension was variously defined by self-report, blood pressure measurements and/or use of anti-hypertensive medications. Sleep duration in virtually every study was ascertained by self-report and presented in several different formats, making comparisons across studies challenging.Most studies demonstrated a positive association between sleep durations of less than 6 hours and overall cardiovascular disease in comparison to sleep durations between 7 and 8 hours. The relationship was stronger for cross-sectional than prospective studies. In contrast, only a few studies demonstrated an association with cardiovascular disease for sleep durations between 6 and 7 hours. For sleep durations greater than 8 hours, the data were more heterogeneous. However, the majority of both cross-sectional and prospective studies found a positive association between sleep duration greater than 9 hours and cardiovascular disease, in comparison to sleep durations of 7–8 hours.Fewer prospective studies were available for hypertension, but similar to overall cardiovascular disease, short sleep durations, especially less than 6 hours were associated with hypertension in comparison to 7–8 hours of sleep. For sleep durations greater than 8 hours, the evidence was less compelling with only a few studies demonstrating a relationship with hypertension.Several meta-analyses that included most of the large cohort studies support these general conclusions. Both "short (≤ 5–6 hours)" and "long (> 8–9 hours)" sleep duration were associated with incident cardiovascular disease in one of these.62 In contrast, another meta-analysis found an association between both short and long sleep and hypertension in cross-sectional studies, but only for short sleep in longitudinal studies.63In summary, elevated risk for both overall cardiovascular disease and hypertension is associated with sleep durations less than 6 hours, and possibly for sleep durations of 6–7 hours compared to sleep durations of 7–8 hours. Evidence for increased risk of cardiovascular disease and hypertension is less compelling for sleep durations greater than 8 hours.3.3 Metabolic HealthExperimental studies and population-based observational studies provide strong evidence for a link between short sleep duration and metabolic function. Experimental sleep restriction reduces cellular and whole body insulin sensitivity, lowers glucose tolerance, and raises afternoon and evening levels of cortisol, an insulin antagonist.64,65 If these effects are prolonged, the increased load on the pancreas can compromise β-cell function and lead to type 2 diabetes.66 Experimental sleep restriction also promotes a positive energy balance by affecting levels of the hunger regulating hormones leptin and ghrelin;27 increasing hunger and appetite,27 with particular cravings for fat and sweet and salty snacks;27,28 increasing caloric intake;27,67 decreasing caloric expenditure through physical activity;68 and increasing body weight.28,67,69 Over time these effects can lead to overweight and obesity which are risk factors for metabolic syndrome and diabetes. The primary limitations of experimental studies is that they examine a short duration of sleep restriction, have small sample sizes with limited generalizability, and restrict sleep to an extreme degree (typically 4 hours per night). The extent to which individuals adapt to the effects of short sleep duration over time is unknown. Conversely, small uncontrolled studies have reported beneficial effects of sleep extension on glucose metabolism and appetite ratings in individuals who habitually curtail their sleep.70,71Numerous cross-sectional and longitudinal population-based observational studies have assessed the relationships between sleep duration and diabetes, obesity, and the metabolic syndrome. Three meta-analyses of prospective studies on sleep duration and diabetes were identified. All three found a significant association between short sleep duration and the incidence of type 2 diabetes.24,72,44 A meta-analysis of cross-sectional studies found a significant negative association between hours of sleep and body mass index; short sleep duration was significantly associated with obesity.73 A meta-analysis of longitudinal studies showed that short sleep duration was associated with incident obesity.74 Two meta-analyses of cross sectional studies found short sleep duration to be associated with the prevalence of the metabolic syndrome.73,74Some studies have also found significant associations between long sleep duration and metabolic outcomes, but the results of meta-analyses relating long sleep duration to metabolic outcomes are mixed. Two meta-analyses showed an association between long sleep duration and incidence of diabetes,24,44 and one meta-analysis showed no relationship.72 In a meta-analysis of longitudinal studies, no relationship was found between long sleep duration and obesity incidence.74 One meta-analysis of cross sectional studies found a significant relationship between long sleep duration and the prevalence of the metabolic syndrome,75 while another meta-analysis found no relationship.76 Given the lack of experimental evidence for detrimental effects of long sleep duration, the observed associations between long sleep duration and metabolic outcomes are often interpreted to reflect residual confounding.3.4 Mental HealthRelationships between sleep duration and psychiatric health have been addressed in numerous publications. These studies vary widely in design, including observational, experimental, and treatment intervention studies; cross-sectional and longitudinal designs; healthy, patient, and population samples; and outcomes including symptom severity or categorical diagnoses. Many studies addressing sleep and mental health focus on insomnia rather than sleep duration per se. Given the number and diversity of published studies and the consensus process aims, strongest consideration was given to cross-sectional and longitudinal epidemiologic studies of self-reported sleep duration in relation to dimensionally or categorically-defined depression.77–84 No published meta-analysis has specifically addressed the relationship between sleep duration and depression, anxiety or other psychiatric disorders.77,79,80,85Short self-reported sleep duration is associated with increased cross-sectional and longitudinal risk for depression, whether measured as symptoms or as a diagnosis.77,79–84,86 The threshold for short sleep varies across studies from 5–7 hours, with the majority using 6 hours. Some data also demonstrate increased risk associated with sleep duration longer than 8–9 hours.80,82 Few studies parsed the specific risk associated with one-hour increments of sleep duration. Sleep duration is also associated with important symptoms related to depression, such as suicidal ideation and psychological distress.77,87,88 Finally, the direction of sleep duration-mental health relationships is not entirely clear. Experimental4,89,90 and longitudinal observational studies88,91 suggest short sleep duration can lead to depression and other mental health symptoms. On the other hand, insomnia symptoms typically improve when depression is treated, even when the treatment does not specifically target sleep.92 Variable effects of depression treatment have been observed on sleep duration per se.93,94 Experimental data are not available to suggest a causal role for long sleep duratio
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