Journal of Occupational & Environmental Medicine:
doi: 10.1097/JOM.0b013e31827759d5
Letters to the Editor

Authors' Response

Buxton, Orfeu M. PhD; Okechukwu, Cassandra A. ScD, MSN, MPH

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Division of Sleep Medicine, Harvard Medical School, Boston, MA.

Department of Medicine, Brigham and Women's Hospital, Boston, MA.

Harvard School of Public Health Center for Work, Health, and Well-being Work, Family, and Health Network

Department of Society, Human Development, and Health, Harvard School of Public Health, Boston, MA.

Harvard School of Public Health Center for Work, Health, and Well-being Work, Family, and Health Network

To the Editor:

Dr Tomoyuki Kawada provided new data on a component of “sleep deficiency,” specifically “sleep insufficiency,” a self-report about a lack of the restorative aspect of sleep. From the results of a multivariate association model including psychosocial factors, self-reported sleep duration was the strongest predictor of sleep sufficiency, more than age, working multiple (day plus evening) shifts, and overall health. Dr Kawada did not include sleep disorder symptoms in his framework. This contrasts with our framework that “sleep insufficiency” is part of “sleep deficiency,” along with inadequate sleep duration and poor sleep quality in the form of insomnia symptoms.1,2

“Sleep deficiency” is a new term recently ratified in November 2011 after a consensus was reached by the Sleep Disorders Research Advisory Board for inclusion of this term in the text of the 2011 National Institutes of Health Sleep Disorders Research Plan. Sleep deficiency is defined as “deficit in the quantity or quality of sleep obtained versus the amount needed for optimal health, performance, and well-being; Sleep deficiency may result from prolonged wakefulness leading to sleep deprivation, insufficient sleep duration, sleep fragmentation, or a sleep disorder, such as in obstructive sleep apnea, that disrupts sleep and thereby renders sleep nonrestorative.”3 The health impact and biopsychosocial determinants of sleep deficiency have been reviewed recently.4

The term is quite clear to a nonspecialist audience, explicitly conveying a sense of the importance of sleep, such that, in its absence, much like a vitamin deficiency, there is likely to be repercussion for sleep being lacking, whatever the precise source of the deficiency. Nonetheless, this definition “a committee could love” for its strong statement and accessible language yields difficulties of operationalization: combining a continuous sleep duration variable, with multiple and potentially overlapping “sleep quality” variables including sleep disorders. Sleep deficiency is relative to an amount and/or quality “needed” that is possible to estimate in expensive laboratory studies as “sleep capacity,” given adequate circumstances, but sleep need can be difficult to measure in population-level studies. Despite any limitations, one important aspect of the ratified definition is that it addresses both sleep quantity and quality. “Sleep deficiency” is also quite like many common terms referring to “sleep quality,” such as those operationalized in the Pittsburgh Sleep Quality Index.5

Dr Kawada's suggestion that having a self-report of sleep insufficiency equates to sleep deficiency, which is contrary to our framework that sleep insufficiency is a component of sleep deficiency, which corresponds to unmet relative sleep need within that individual. In our Venn diagram (Figure 1),2 we depict multiple components of sleep deficiency in a sample of more than 1500 health care workers. Note the lack of complete overlap of sleep insufficiency with either short sleep duration (fewer than 6 h/night) or presence of insomnia symptoms. The self-report of never or rarely having restorative sleep seems unreliably related to even severe insomnia symptoms (3 or more per week for last month of difficulty getting to sleep, staying asleep, or waking up too early). Dr Kawada did not include insomnia symptoms; thus, it is expected that the greatest overlap in his results is with the only other sleep variable included in the model, sleep duration.

The prevalence of insomnia symptoms in Kawada's sample of mostly middle-aged male workers is unknown. In our sample of mostly healthy, midlife women, snoring symptoms were so low in frequency that we did not include apnea risk in our sleep deficiency framework. In samples enriched for men, obesity, and/or older age, apnea risk, and the commonly elevated sleepiness and sense of nonrestorative sleep, though not endorsed by all individuals, would be a strong predictor of sleep insufficiency. These issues are not addressed in the study by Kawada and colleagues.

Another important consideration in any attempt to define sleep-related outcomes is the sociodemographic characteristic of the study sample. For example, women are more likely than men to suffer from insomnia symptoms but men are more likely to have obstructive sleep apnea.6 Also, ethnoracial and socioeconomic disparities in sleep-related outcomes have come to light in the United States.79 Therefore, careful considerations must be made before making broad conclusions based on studies with limited sociodemographic diversity (such as Buxton et al's study of mostly middle-aged women and Kawada's study of middle-aged male workers). In a separate sample of nursing home workers, we explored the ethnoracial differences of 1 hour in mean, nightly, measured sleep duration between white and African/Caribbean immigrant workers in long-term-care facilities. Although workplace disparities were present in this sample, the factors primarily explaining this difference were long working hours and night-work schedule (ie, being on shift for at least 6 hours between 10 PM and 6 AM).10

In the absence of firmer measures of sleep need, it may be difficult to sensitively ascertain the presence of sleep deficiency as an “Unmet Public Health Need,” to borrow the title of a recent Institute of Medicine report.11 Modifiable psychosocial factors, especially workplace factors, which are strongly related to sleep deficiency and wellness outcomes,1 pain, and functional and workplace limitations,2 are especially fruitful areas for future interventions.

Orfeu M. Buxton, PhD

Division of Sleep Medicine,

Harvard Medical School,

Boston, MA.

Department of Medicine,

Brigham and Women's Hospital,

Boston, MA.

Harvard School of Public Health Center for Work, Health, and Well-being

Work, Family, and Health Network

Cassandra A. Okechukwu, ScD, MSN, MPH

Department of Society, Human Development, and Health, Harvard School of Public Health,

Boston, MA.

Harvard School of Public Health Center for Work, Health, and Well-being

Work, Family, and Health Network

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REFERENCES

1. Sorensen G, Stoddard AM, Stoffel S, et al. The role of the work context in multiple wellness outcomes for hospital patient care workers. J Occup Environ Med/Am Coll Occup Environ Med. 2011;53:899–910.

2. Buxton OM, Hopcia K, Sembajwe G, et al. Relationship of sleep deficiency to perceived pain and functional limitations in hospital patient care workers. J Occup Environ Med/Am Coll Occup Environ Med. 2012;54:851–858.

3. National Institutes Of Health. 2011 Sleep Disorders Research Plan. Available at: http://go.usa.gov/I4tNovember 2011. Accessed September 12, 2012.

4. Knutson KL. Sociodemographic and cultural determinants of sleep deficiency: implications for cardiometabolic disease risk. Soc Sci Med. 2012 May 26 [epub ahead of print].

5. Buysse DJ, Reynolds CF III, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh sleep quality index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989;28:193–213.

6. Al Lawati NM, Patel SR, Ayas NT. Epidemiology, risk factors, and consequences of obstructive sleep apnea and short sleep duration. Prog Cardiovasc Dis. 2009;51:285–293.

7. Patel NP, Grandner MA, Xie D, Branas CC, Gooneratne N. Sleep disparity” in the population: poor sleep quality is strongly associated with poverty and ethnicity. BMC Public Health. 2010;10:475.

8. Hale L, Peppard PE, Young T. Does the demography of sleep contribute to health disparities. In: Pandi-Perumal SR, Leger D eds. Sleep Disorders: Their Impact on Public Health. London, UK: Informa Healthcare; 2007:1–17.
9. Hale L, Do DP. Racial differences in self-reports of sleep duration in a population-based study. Sleep. 2007;30:1096.

10. Ertel KA, Berkman LF, Buxton OM. Socioeconomic status, occupational characteristics, and sleep duration in African/Caribbean immigrants and US white health care workers. Sleep. 2011;34:509.

11. Institute of Medicine Committee on Sleep Medicine Research, Board on Health Sciences Policy. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington, DC: The National Academies Press; 2006.

©2012The American College of Occupational and Environmental Medicine

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