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Association between sleep duration and body size differs among three Hispanic groups.

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AMERICAN JOURNAL OF HUMAN BIOLOGY 23:138–141 (2011)
Short Report
Association Between Sleep Duration and Body Size Differs Among Three
Hispanic Groups
KRISTEN L. KNUTSON*
Department of Medicine, University of Chicago, Chicago, Illinois 60637
Objectives: Although numerous studies have reported negative associations between sleep duration and body size,
no studies of this association have focused on Hispanic groups, which was the goal of this work.
Methods: Data are from adults in the 1982–1984 Hispanic Health and Nutrition Examination Survey (HHANES),
which enrolled Cuban-Americans, Mexican-Americans, and Puerto Ricans. HHANES included self-reported sleep duration and several anthropometric measures. Principle component analysis extracted a single variable to represent body
size. Linear regression models stratified by Hispanic group predicted body size from sleep duration adjusting for age,
sex, education, income, marital status, household size, and acculturation.
Results: Average age was 36–44 years and 52–64% were women. Average sleep duration was 7.3–7.7 h. Shorter sleep
duration was associated with larger body size in Mexican-Americans only. The regression coefficient indicated that on
average a Mexican-American adult who reported sleeping for 4 h would have a body size that was larger by 0.12 times
the standard deviation for body size than a Mexican-American adult reporting 8 h of sleep (all other covariates being
equal). This effect was similar to the effect of 10 years of age, which would be associated with an increase in body size
by 0.10 times the standard deviation of body size.
Conclusions: These results underscore the importance of examining factors associated with obesity in different ethnic groups. It may be inappropriate to combine different Hispanic ethnicities together. Am. J. Hum. Biol. 23:138–141,
2011.
' 2010 Wiley-Liss, Inc.
The prevalence of obesity in the United States has more
than doubled in the last 30 years. The obesity epidemic, however, has been more extensive among minority groups than
among non-Hispanic whites (Anonymous, 2009). For example, obesity rates are higher in Mexican-Americans (36.8%)
compared to whites (30%) (Ogden et al., 2006). This disparity
in obesity is not a recent phenomenon. In 1976–1980, rates of
obesity were higher in Mexican-Americans (20.6%) than in
non-Hispanic whites (13.4%) (Flegal et al., 1998). Obesity is a
major risk factor for type 2 diabetes, cardiovascular disease,
and some cancers, all of which are associated with shorter
life expectancy, reduced quality of life, and increased economic burden (Ettaro et al., 2004; Franco et al., 2007; Solomon and Manson, 1997; Wolf and Colditz, 1998). As such,
much effort has been dedicated to determining risk factors
for obesity and potential interventions to reduce obesity rates.
One potential novel risk factor may be short sleep duration.
Sleep duration has been associated with obesity in over 60
published articles. These studies have reported negative associations between self-reported sleep duration and body size,
particularly, body mass index (BMI) (see Knutson, 2010 for a
review). The majority of these studies combined different
racial and ethnic groups and did not examine the association
between sleep and body size for each ethnic group separately.
Furthermore, few published studies have provided data on
the sleep characteristics of Hispanic groups (Loredo et al.,
2010). Given the large disparities in obesity risk between
non-Hispanic whites and Hispanic groups, it is important to
determine the risk factors for obesity among Hispanic groups
specifically. The aim of this work was to examine the relationship between self-reported sleep duration and body size in
three Hispanic groups: Cuban-Americans, Mexican-Americans, and Puerto-Ricans. These data are from 1982 to 1984,
which precedes the current ‘‘obesity epidemic’’ but not the
ethnic disparity in obesity prevalence.
C 2010
V
Wiley-Liss, Inc.
METHODS
Sample
This analysis used data from the Hispanic Health and
Nutrition Examination Survey (HHANES) [1985; U.S.
Dept of Health and Human Services and National Center
for Health Statistics (1992)], which was conducted in
1982–1984. The sample design of HHANES was similar to
that used by previous National Health and Nutrition Examination Surveys (NHANES) and involved complex,
multistage, stratified, and probability cluster samples.
HHANES recruited individuals from three HispanicAmerican population subgroups: (1) Mexican-Americans
from Texas, Colorado, New Mexico, Arizona, and California, (2) Cuban-Americans from Dade County, Florida, and
(3) Puerto Ricans from the New York City area, including
parts of New Jersey and Connecticut. Data collection
included a household interview with several questionnaires and a physical examination. The analyses presented here included adults only (18 years).
Measurements
The household interview was conducted in either English or Spanish according to the participant’s preference.
Self-reported sleep duration was assessed by the following
*Correspondence to: Kristen L. Knutson, Department of Medicine/Section of Pulmonary and Critical Care, University of Chicago, 5841 S. Maryland Avenue, MC 6076, Chicago, IL 60637, USA.
E-mail: kknutson@medicine.bsd.uchicago.edu
Received 3 August 2010; Revision received 30 August 2010; Accepted 14
September 2010
DOI 10.1002/ajhb.21108
Published online 15 November 2010 in Wiley Online Library
(wileyonlinelibrary.com).
139
SLEEP AND BODY SIZE IN THREE HISPANIC GROUPS
question, ‘‘On the average, about how many hours of sleep
do you get each day, that is, during a 24-hour period?’’
Responses were in whole hours and ranged from 1 to 20 h.
The following measurements were taken as part of the
physical examination: height, weight, upper arm circumference, medial calf circumference, medial calf skinfold,
triceps skinfold, iliac crest skinfold, and subscapular
skinfold. All measurements, except skinfolds, were taken
to the nearest tenth of a centimeter, and skinfold measurements were taken to the nearest half of a millimeter.
BMI was calculated as weight (kg) divided by height
(meters) squared. Rather than examining each anthropometric measurement in separate regression analyses,
which would increase the chance of type 1 error due to
multiple comparisons, principal components analysis
was performed on all body measurements, and the first
component was extracted to represent body size. The
eigenvalues for this component ranged from 4.3 to 4.8 for
the three Hispanic groups, and all anthropometric measurements had positive loadings on this component. Thus,
a larger value for this principle component (PC) represented larger overall body size. Finally, the PC was converted to a standardized z in order to facilitate interpretation.
Covariates included in these analyses were age, sex,
educational level, income, marital status, household size,
and two acculturation measures. Educational level was
determined by the highest grade or year of regular school
the participant ever attended, and answers ranged from 0
(never attend school) to 17 years (graduate school). Total
combined family income was dichotomized by the
HHANES investigators as above or below $20,000 per
year. This is consistent with the median household income
reported for Hispanics in the United States in 1985
(United States. Bureau of the Census, 1985). Martial status was grouped into the following three categories: married, widowed, divorced or separated, and never married.
Household size was the total number of persons living in
the same residence, including the participant, and
answers ranged from 1 to 18 persons. The two acculturation measures, which have been used previously (Solis
et al., 1990), included language use and birthplace of the
respondent and his/her parents. The language use variable was the mean of the response to four questions that
asked the respondent which language he/she spoke,
wrote, read, and preferred. The responses to these questions were (1) Spanish only, (2) Mostly Spanish (3) Spanish and English equally, (4) Mostly English, and (5) English Only. Respondents also indicated whether they and
their parents were born in the US or elsewhere. Answers
were grouped into ‘‘first generation’’ (respondent and parent were foreign-born), ‘‘second generation’’ (respondent
was US-born but parents foreign-born), and ‘‘third generation or higher’’ (respondent and parent were US-born).
Because only 1% of the Cuban-American sample and 3%
of the Puerto Rican sample were third generation or
higher, this variable was dichotomized into first generation or second generation or higher.
Statistical analysis
Because of the complex sampling design, analysis must
be stratified by the three ethnic groups, which means
comparison among groups cannot be calculated (1985).
Thus, all analyses presented here are stratified by ethnic
group. Analyses were calculated using the survey command in Stata/SE (version 10.1, College Station, Texas)
identifying strata and primary sampling units and
included the sample weights. Means or proportions and
their 95% confidence intervals were estimated for each
variable. Hierarchical linear regression models were estimated to predict the z-score for the PC for body size. The
first model included only the covariates, and the second
model added sleep duration. A quadratic term for sleep
duration was added to the model to test for a curvilinear
association.
RESULTS
The demographic, sleep, and anthropometric characteristics for each ethnic group are presented in Table 1. Average age was between 36 and 44 years and between 52 and
64% of the samples were women. Average self-reported
sleep duration was lowest among Cuban-Americans (7.3
h) and highest among Mexican-Americans (7.7 h). Fewer
of the Mexican-Americans were first generation than
observed among the Cuban-Americans and PuertoRicans.
Table 2 presents the results of the final model from
hierarchical linear regression analyses predicting the zscore for the PC for body size in each ethnic group separately. In the Mexican-American group, shorter sleep duration was associated with larger body size after adjustment for the covariates. On average, a Mexican-American adult who reported sleeping 4 h would have a body
size that was larger by 0.12 times the standard deviation
for body size than a Mexican-American adult reporting 8
h of sleep (all other covariates being equal). This effect
was similar to the effect of 10 years of age, which would
be associated with an increase in body size by 0.10 times
the standard deviation of body size. There was no apparent association between sleep duration and body size in
either Cuban-Americans or Puerto Ricans. The quadratic
term for sleep duration was not significant in any of the
three ethnic groups (data not shown). In the MexicanAmerican sample, the r2 value for the model with only
the covariates was 0.093 and increased to 0.096 when
sleep duration was added, a small, but significant change
(P 5 0.003). Similar small but significant r2 changes
were observed in the Cuban-American sample (0.0762–
0.0766, P 5 0.0004) and in the Puerto Rican sample
(0.100–0.102, P 5 0.002).
DISCUSSION
In the HHANES data, the association between selfreported sleep duration and body size was not consistent
among the three Hispanic groups. A significant negative
association between sleep and body size, as has been
reported in numerous previous studies, was detected only
among the Mexican-Americans. These results underscore
the importance of examining factors associated with obesity in different ethnic groups. Furthermore, it may be
inappropriate to group different Hispanic ethnicities together, because these results demonstrated differences
among Cuban-Americans, Mexican-Americans, and
Puerto Ricans. Differences in sleep disturbances have
been reported between African-American subgroups as
well: those born in the United States reported more sleep
disturbances than those born in the Caribbean (JeanAmerican Journal of Human Biology
140
K.L. KNUTSON
TABLE 1. Demographic, anthropometric, and sleep characteristics of the three Hispanic groupsa
n
Age (years)
Sleep duration (h)
BMI (kg/m2)
Arm circumference (cm)
Calf circumference (cm)
Calf skinfold (mm)
Iliac skinfold (mm)
Subscapular skinfold (mm)
Triceps skinfold (mm)
Educational level (highest grade)
Household size (persons)
Language use
Female
Income $20,000
Marital status
Married
Widowed, divorced, or separated
Never married
Generation in the United States
First generation
Second generation
Third generation or higher
Cuban-Americans
889
Mean (95% CI)
Mexican-Americans
3,520
Mean (95% CI)
Puerto Ricans
1,316
Mean (95% CI)
43.5 (42.0–45.2)
7.3 (7.2–7.5)
25.8 (25.3–26.3)
31.0 (30.6–31.3)
35.7 (35.5–35.9)
17.0 (16.7–17.3)
24.6 (23.7–25.5)
22.9 (22.2–23.5)
20.4 (19.7–21.1)
10.5 (10.1–10.9)
3.4 (3.2–3.7)
2.1 (2.0–2.2)
%
56
43
36.0 (35.1–36.8)
7.7 (7.6–7.8)
26.2 (25.9–26.5)
31.4 (31.2–31.5)
35.8 (35.6–35.9)
15.3 (14.4–16.3)
25.2 (23.6–26.9)
22.2 (21.0–23.5)
19.8 (19.1–20.4)
9.4 (8.9–9.8)
4.3 (4.2–4.5)
3.0 (2.9–3.1)
%
52
35
36.0 (34.8–37.2)
7.4 (7.2–7.5)
25.8 (25.4–26.2)
30.6 (30.1–31.1)
36.5 (36.2–36.8)
15.1 (14.2–16.0)
23.3 (22.9–23.7)
21.5 (21.0–21.9)
20.1 (18.9–21.3)
10.2 (9.9–10.6)
3.9 (3.6–4.1)
2.9 (2.7–3.0)
%
64
29
67
17
16
69
13
18
48
23
30
96
3
1
37
23
40
70
27
3
a
Mean (95% CI) unless otherwise noted.
TABLE 2. Results from linear regression analysis predicting the z score of the principle component of body size stratified by Hispanic group
Cuban-Americans
b (95% CI)
Sleep duration (h)
Age (past 18 years)
Sex (0 5 male)
Educational level (years)
Marital status
Married
Widowed, divorced, or separated
Never married
Income (0 $20,000/year)
Household size (centered at 1 person)
Language use
Generation (0 5 first generation)
Constant
Mexican-Americans
b (95% CI)
Puerto Ricans
b (95% CI)
20.01 (20.06–0.04)
0.01 (0.001–0.01)
0.25 (0.17–0.34)
0.01 (20.01–0.03)
20.03 (20.06 – 20.004)
0.01 (0.002–0.01)
.36 (0.27–0.46)
0.01 (20.003–0.02)
20.02 (20.06–0.01)
0.01 (0.01–0.01)
0.38 (0.25–0.51)
0.01 (20.003–0.02)
Referent
20.13 (20.29–0.04)
20.15 (20.41–0.10)
0.02 (20.11–0.15)
0.03 (20.01–0.06)
20.01 (20.08–0.06)
20.27 (20.50 – 20.05)
0.15 (20.18–0.49)
Referent
20.10 (20.21–0.01)
20.16 (20.25 – 20.07)
0.04 (20.03–0.11)
0.03 (0.01–0.04)
20.09 (20.16 – 20.03)
0.24 (0.08–0.39)
0.29 (0.04–0.54)
Referent
0.02 (20.17–0.22)
20.09 (20.25–0.07)
0.04 (20.09–0.16)
0.03 (20.004–0.06)
20.04 (20.11–0.03)
20.08 (20.23–0.07)
0.06 (20.20–0.32)
Louis et al., 2001). The reasons why these associations differ should be explored as they may help to elucidate the
mechanisms underlying the association between selfreported sleep duration and body size. Biocultural factors,
such as dietary intake and physical activity, may mediate
the association between self-reported sleep duration and
body size. In addition, some of these biocultural factors
may either aggravate or protect against the effects of
short sleep, which could provide potential targets for
interventions to prevent obesity.
The strength of this study was that between 800 and
3,500 adults in each of three Hispanic ethnicities were enrolled. There were some limitations, however, that should
be noted. First, sleep duration was self-reported, which
has been shown to be only moderately correlated with
actigraphically estimated sleep duration (Lauderdale
et al., 2008). In addition, these data were collected over 25
years ago, which is when the rapid increase in obesity
rates was just beginning. Nonetheless, even in the early
1980s, the prevalence of obesity among Mexican-Americans was over 20% and was higher than that observed in
American Journal of Human Biology
non-Hispanic whites (Flegal et al., 1998). Moreover, the
proportion of short sleepers appears to have increased
over this same time period (National Center for Health
Statistics, 2005), particularly among full-time workers
(Knutson et al., 2010). Only 3–5% of the HHANES ethnic
groups reported sleeping less than 6 h, while the 2010
Sleep in America Poll found that 17% of Hispanics
reported sleeping less than 6 h (National Sleep Foundation, 2010). If there were too few short sleepers in the
HHANES data to detect an association between sleep and
body size, it is possible that sleep duration may have a
stronger association with body size in these Hispanic
groups today. Future research needs to enroll persons
from different ethnicities and consider whether combining
people into single ethnic or racial groups, such as ‘‘Hispanic,’’ is appropriate.
LITERATURE CITED
Anonymous, 2009. Differences in prevalence of obesity among black, white,
and Hispanic adults—United States, 2006–2008. MMWR Morb Mortal
Wkly Rep 58:740–744.
SLEEP AND BODY SIZE IN THREE HISPANIC GROUPS
Ettaro L, Songer TJ, Zhang P, Engelgau MM. 2004. Cost-of-illness studies
in diabetes mellitus. Pharmacoeconomics 22:149–164.
Flegal K, Carroll M, Kuczmarski F, Johnson C. 1998. Overweight and obesity in the United States: prevalence and trends, 1960–1994. Int J Obes
Relat Metab Disord 22:39–47.
Franco OH, Steyerberg EW, Hu FB, Mackenbach J, Nusselder W. 2007.
Associations of diabetes mellitus with total life expectancy and life expectancy with and without cardiovascular disease. Arch Intern Med
167:1145–1151.
Jean-Louis G, Magai CM, Cohen CI, Zizi F, von Gizycki H, DiPalma J,
Casimir GJ. 2001. Ethnic differences in self-reported sleep problems in
older adults. Sleep 24:926–933.
Knutson KL, Van Cauter E, Rathouz PJ, DeLeire T, Lauderdale DS. 2010.
Trends in the prevalence of short sleepers in the USA: 1975–2006. Sleep
33:37–45.
Lauderdale DS, Knutson KL, Yan LL, Liu K, Rathouz PJ. 2008. Selfreported and measured sleep duration: how similar are they? Epidemiology 19:838–845.
Loredo JS, Soler X, Bardwell W, Ancoli-Israel S, Dimsdale JE, Palinkas
LA. 2010. Sleep health in U.S. Hispanic population. Sleep 33:962–967.
National Center for Health Statistics. 1985. Plan and operation of the
Hispanic Health and Nutrition Examination Survey 1982–84. Vital
and Health Statistics. Series 1, No. 19. DHHS Pub. No. (PHS) 85–1321.
Public Health Service. Washington, DC. U.S. Government Printing
Office.
141
National Center for Health Statistics. 2005. QuickStats: percentage of
adults who reported an average of 6 hours of sleep per 24-hour period,
by sex and age group—United States, 1985 and 2004. MMWR Morb
Mortal Wkly Rep 54:933.
National Sleep Foundation. 2010, Sleep in America poll. Washington, DC.
Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM.
2006. Prevalence of overweight and obesity in the United States, 1999–
2004. JAMA 295:1549–1555.
Solis JM, Marks G, Garcia M, Shelton D. 1990. Acculturation, access to
care, and use of preventive services by Hispanics: findings from
HHANES 1982–84. Am J Public Health 80 (Suppl):11–19.
Solomon CG, Manson JE. 1997. Obesity and mortality: a review of the epidemiologic data. Am J Clin Nutr 66 (4 Suppl):1044S–1050S.
U.S. Dept of Health and Human Services, National Center for Health Statistics. 1992. Hispanic Health and Nutrition Examination Survey, 1982–
1984 [Computer file]. 8th ICPSR release. Hyattsville, MD: U.S. Dept of
Health and Human Services, National Center for Health Statistics [producer]. Ann Arbor, MI: Inter-university Consortium for Political and
Social Research [distributor], 1993.
United States. Bureau of the Census. 1985. Money income and poverty status of families and persons in the United States.Current population
reports. Series P-60, Consumer income. Washington, D.C.: U.S. Department of Commerce For sale by the Supt. of Docs. p 216.
Wolf AM, Colditz GA. 1998. Current estimates of the economic cost of obesity in the United States. Obes Res 6:97–106.
American Journal of Human Biology
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