SCIENCE science.org 29 OCTOBER 2021 • VOL 374 ISSUE 6567 553CREDITS: GRAPHIC K. FRANKLIN/
SCIENCE
; DATA CHEN
ET AL
., SLEEP
,^38
, 6, 2015
O
n a Sunday morning earlier this
month, Girardin Jean-Louis at-
tended the regular mass service
at Trinity Baptist Church in North
Miami, Florida. He wasn’t just
there to worship, though. After the
hourlong service, he stepped to
the lectern, microphone in hand,
and spoke to the congregation—
most of them Black—about the importance
of good sleep. “I was using the Bible, talking
about how important sleep used to be for all
of the kings and queens,” he says. “They al-
ways had a sage [who] would interpret the
dreams, so I use this to show dreaming is
very important.”
A sleep researcher at the University of
Miami, Jean-Louis splits his time between
the lab, where he studies the disproportion-
ate toll of sleep deficiency on communities
of color, and places at the center of many
Black communities: churches, barber-
shops, beauty salons. There, with the help
of pastors, barbers, and other influential
figures, he preaches the importance of
sleep. Being a Baptist helps, too, he says. “I
know the language, I know the lingo.”
He is trying to address a historically ne-
glected aspect of racial inequity. Far more
Black and Hispanic people than white
people report routinely getting less than
6 hours of sleep, well short of the recom-
mended 7 to 9 hours for adults. Studies
have shown nonwhite people take longer
to fall asleep, wake up more during the
night, and spend less time in deep sleep—a
stage of sleep important for strengthening
the immune system, forming memories,
and restoring the health of cells. Sleep dis-
orders, such as obstructive sleep apnea, are
up to twice as common in people of color.
All of this increases the risk of chronic dis-
eases aggravated by poor sleep. “Sleep is
a privilege,” says Dayna Johnson, a sleep
epidemiologist at Emory University. “If
we can target sleep, we might be able to
reduce the burden of all types of diseases
among racial minorities.”
Researchers like Johnson and Jean-
Louis are trying to understand what causes
these disparities and how scientists, physi-
cians, and policymakers might implement
solutions—and begin to right what they
see as an underappreciated source of so-
cial and health injustice. “Sleep deficiency
is literally undermining the fabric of soci-
ety, particularly in minority and low socio-
economic populations, because they bear
the disproportionate burden of the asso-ciated risk,” says neurobiologist Marishka
Brown, director of the National Center on
Sleep Disorder Research at the National
Heart, Lung, and Blood Institute. “Sleep is
a modifiable source of inequity.”JEAN-LOUIS FIRST became interested in sleep
disparities when he was a postdoctoral re-
searcher in psychiatry at the University of
California, San Diego, in the late 1990s. In a
survey study, he and colleagues found non-
white men in San Diego slept about 1 hour
less per night on average than white men.
Jean-Louis recalls wondering why at the
time: “Is it a function of health care access?
Is it a function of lifestyle factors?”Some evidence points to biological
factors—such as differences in upper airway
anatomy that might make people of Asian
descent more prone to sleep apnea, in which
soft throat tissue obstructs the airway and
causes waking. But most researchers think
socioeconomic and environmental factors
are the main cause of these disparities. “I
want to move attention away from those ge-
netic explanations because what that means
is that it’s that person’s individual responsi-
bility to fix that issue, versus shining a light
on the structural and social factors,” says
Carmela Alcántara, a clinical psychologist
at Columbia University.
In recent decades, researchers have iden-
tified some of those social and environ-
mental factors. For example, more Black
and Hispanic people work nontraditional
hours, including night shifts, which makes
it difficult for them to get a good night’s
sleep. A 2010 study of 340 workers at anextended-care facility in Massachusetts,
for example, found Black and Hispanic
employees were twice as likely as white
ones to work the night shift and slept up to
1 hour less per day on average than white
people in general.
Although shift work affects sleep in all
ethnic groups, Hispanic people, especially
those who are unemployed, may experience
a more specific sleep disrupter. Alcántara’s
research has found acculturation stress—
distress that results from adapting and in-
tegrating into a new culture—increases the
severity of insomnia symptoms. “There’s
something unique for this population
about this specific sociocultural stressor.”
In addition, discrimination related to their
ethnicity and status as immigrants also
affects sleep in Hispanic people, she says.
Indeed, more than a dozen studies have
identified racial discrimination as a con-
tributor to sleep disparities. In one pub-
lished last year, Johnson and colleagues
asked 1458 people in Detroit who met
clinical criteria for insomnia how often
they have been treated badly or unfairly
because of their race or ethnicity. Black
people reported more discrimination and
more severe insomnia symptoms than
white people, and a statistical analysis
determined discrimination accounted for
60% of their insomnia severity.
Environmental factors also cut into
sleep. A 2020 study that combined data
from the U.S. census with an atlas of light
pollution derived from satellite data found
Black, Hispanic, and other people of color
tend to reside in brighter areas, where
they are exposed to approximately twice
as much ambient light at night as white
people. Exposure to artificial light from the
street and commercial buildings has been
found to suppress melatonin—a hormone
that helps initiate sleep. That causes peo-
ple to fall asleep later at night, resulting in
poorer sleep overall.
Black, Hispanic, and Asian people in the
United States are also exposed to dispropor-
tionately high levels of particulate air pollu-
tion. Exposure to this type of pollution can
cause inflammation of the nose and throat,
and some evidence suggests chronic expo-
sure can worsen sleep apnea and increase
daytime sleepiness. And then there is night-
time noise, which a 2017 study at hundreds
of sites across the United States found is
higher in neighborhoods with a higher pro-
portion of Black residents.
“Our ZIP code is as—if not more—
important than our genetic code,” Johnson
says.“SLEEP IS THE MOST primordial human ac-
tivity,” says Azizi Seixas, a precision medi-Researchers are starting to understand the
social and environmental factors that contribute
to poor sleep—and increase the risk of health
problems—in communities of color.White14.634.431.619.3Black- 5
16.4
32.743.4Hispanic13.32530.231.5Chinese
American8.3
2826.63 7. 1020406080100Percent of participants< 6 hours 6–7 hours 7–8 hours ≥ 8 hoursSleep durationAnother inequity
A 2015 study of 2230 people in six U.S. communities
found people of color were much more likely than white
people to sleep less than 6 hours per night on average.