Abstract

Free 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: Search for more papers by this author , 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 Search for more papers by this author , M. Safwan Badr, MD Wayne State University, Detroit, MI Search for more papers by this author , Gregory Belenky, MD Washington State University, Spokane, WA Search for more papers by this author , Donald L. Bliwise, PhD Emory University, Atlanta, GA Search for more papers by this author , Orfeu M. Buxton, PhD Pennsylvania State University, University Park, PA Search for more papers by this author , Daniel Buysse, MD University of Pittsburgh, Pittsburgh, PA Search for more papers by this author , David F. Dinges, PhD University of Pennsylvania, Philadelphia, PA Search for more papers by this author , James Gangwisch, PhD Columbia University, New York, NY Search for more papers by this author , Michael A. Grandner, PhD, MSTR, CBSM University of Pennsylvania, Philadelphia, PA Search for more papers by this author , Clete Kushida, MD, PhD Stanford University, Stanford, CA Search for more papers by this author , Raman K. Malhotra, MD Saint Louis University, St. Louis, MO Search for more papers by this author , Jennifer L. Martin, PhD University of California, Los Angeles, Los Angeles, CA Search for more papers by this author , Sanjay R. Patel, MD, MSc Harvard Medical School, Boston, MA Search for more papers by this author , Stuart F. Quan, MD Harvard Medical School, Boston, MA Search for more papers by this author , Esra Tasali, MD The University of Chicago, Chicago, IL Search for more papers by this author 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 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