Sleep health study in Bangladesh provides a nuanced understanding of childhood obesity
May/June 2025 | Volume 24 Number 3
Photo courtesy of Ayesha SaniaA participant in Dr. Ayesha Sania's study in Bangladesh.
Bangladesh, a densely populated, lower-middle-income country in South Asia, is home to approximately 170 million people.
“When we think about the children of Bangladesh, we usually think of stunting,” says Dr. Ayesha Sania, an assistant professor at Columbia University Irving Medical Center. (Stunting is impaired childhood growth and development due to poor nutrition.) “Yet Bangladesh has a dual burden of malnutrition—this means a high rate of stunting (though this is decreasing)—while obesity among children is increasing at a concerning pace.”
Sania is examining sleep health as it relates to cognitive development and obesity in Bangladeshi children for her Fogarty
International Research Scientist Development Award (IRSDA) project. She notes that, between 2003 and 2015, childhood obesity in Bangladesh more than doubled from 3.6% to 7.9%, while recent reports indicate that approximately 14% of children between ages 4 and 7 are obese.
Similar striking shifts over relatively short periods can be seen in many low- and middle- income countries (LMICs), alongside an identical dual burden of malnutrition and obesity. “These changes reflect the broader lifestyle transitions happening in many LMICs,” says Sania.
Urgency required
As swift urbanization occurs in many LMICs, socioeconomic differences widen. “Urban families often live in small, densely packed apartments with limited or no space for children to play or be physically active,” says Sania.
Meanwhile, processed foods, fast food, and high-calorie snacks increasingly replace home-cooked meals. Kids are spending more time on screens, which not only reduces opportunities for physical activity but also interferes with sleep. “Meta-analyses have shown that short sleep duration is associated with increased obesity risk in children.”
Sania explains that shorter sleep duration disturbs the metabolic hormones—such as leptin, insulin and cortisol—as well as the growth hormones, and these then disrupt metabolic regulation resulting in higher obesity rates. “We also hypothesize a bidirectional relationship between executive function and obesity,” says Sania. (Executive function, which includes self-control, cognitive flexibility, and working memory, begins to emerge around age 3 and then rapidly develops through age 6.)
On the one hand, a child cannot stop eating due to poor executive function (poor impulse control), while, on the other hand, elevated hormones induced by obesity are modifying brain activity resulting in poor executive function.
“This complex interplay between sleep, executive function, and obesity could help us understand childhood obesity in a more nuanced way,” says Sania.
Photo courtesy of Ayesha SaniaA study participant sleeps, wearing an actigraphy watch to collect data.
Childhood sleep deficits
Preliminary data for Sania’s Fogarty project show that roughly 40% of preschool children in Bangladesh slept less than what
WHO recommends for the age group. Across all LMICs, emerging data highlight similar trends favoring later bedtimes and shorter nighttime sleep for children.
“It's a big problem, yet also a big opportunity where we can make a change,” says Sania. Research in high-income settings suggests that several features influence and predict sleep, including individual factors (such as screen time and physical activity), interpersonal factors (including maternal depression and parental stress), and family and social factors (socioeconomic status and household crowding).
“However, we still don’t fully understand how these factors play out in LMICs where the context is quite different.” Her study of children in Bangladesh relies on wearable devices (actigraphy watches) to collect sleep data that “will deepen our understanding of the relationship between sleep health (and other lifestyle factors including physical activity and diet), executive function, and obesity risk,” says Sania. Her team also plans to adapt and evaluate a sleep promotion intervention tailored to the local context.
“If the intervention proves feasible, then we hope to study its impact on sleep health practices and obesity outcomes in a larger randomized trial.” Overall, she hopes to gain valuable knowledge about preschool children in Bangladesh, while creating a pipeline of knowledge on which the scientific community can build.
As of May, Sania’s team had enrolled 256 of its 300 target participants and processed 140 actigraphy readouts. In 2024 the team faced delays due to political instability, yet things are running smoothly now primarily thanks to her Bangladesh mentor, Dr. Shams El Arifeen, and his team. “We were initially worried about losing the actigraphy watches (generously donated by the lab of my U.S. mentor, Dr. William Fifer), but, so far, we’ve only lost one.”
Meanwhile, many children have been wearing the watches for 10, 11, or even 14 days instead of just seven required days. “This ‘bonus’ data will be very helpful as we measure day-to-day variability in bedtime, nap time, and sleep duration.”
Photo courtesy of Ayesha SaniaParents begin enrollment of their child into Dr. Sania's study.
Benefits for Americans
When we sleep, where we sleep, and how we sleep may be cultural, but the biological aspects of sleep health, including the relationship between sleep, executive function, and obesity risk, are universal, says Sania. Insights gained from her study will be “broadly applicable, especially for children in similar sociocultural contexts, such as those in South Asia and even in the U.S.”
Children living in poor neighborhoods and small apartments, whether in New York or Dhaka, lead similar lives, she adds. “Many solutions developed in one context have been successfully adapted to others. For instance, I am adapting an intervention originally created for low-income families in the U.S., while one of my mentors has brought another intervention developed in LMICs to the U.S.”
“Science often transcends borders,” says Sania, whose research spans the U.S., South Africa, Tanzania, and Bangladesh. “I carry lessons from every context into my current work, and that mosaic of experiences informs and inspires me, enabling me to support populations facing similar challenges anywhere on the globe.”
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