Climate change costs Bangladeshis up to 84hr sleep a year: Study

Climate change is increasingly disrupting sleep across Bangladesh, with people in major cities now losing up to 84 hours of sleep annually because of rising nighttime temperatures, according to a new analysis by Climate Central released yesterday (15 July).

The report, Climate Change is Costing People Sleep, found that climate change's contribution to temperature-related sleep loss has doubled or more in every major Bangladeshi city analysed since the early 1970s, raising concerns about its growing impact on public health, productivity and well-being.

According to the analysis, residents of Bangladesh's major cities now lose between 72 and 84 hours of sleep every year due to hot nights. In Dhaka and Rajshahi, climate change's share of annual sleep loss increased from 3% during 1970-1975 to 6% in 2020-2025, representing a 100% rise.

The increase was even sharper in Cumilla and Rangpur, where climate change's contribution rose from 3% to 7% over the same period, an increase of more than 130%.

Among the cities analysed, Chattogram recorded the highest annual sleep loss at 84 hours during 2020-2025, followed by Khulna with 79 hours. Dhaka and Rajshahi each recorded 76 hours, Gazipur and Cumilla 74 hours, while Rangpur registered 72 hours.

Within Dhaka, residents of Mirpur and Pallabi lost an estimated 77 hours of sleep annually, while those in Mohammadpur lost around 73 hours.

The Bangladesh findings reflect a broader global trend. Across 1,338 major cities worldwide, annual temperature-related sleep loss increased by 9.5%, from 45.6 hours per person during 1970-1975 to 49.9 hours during 2020-2025.

More significantly, annual sleep loss directly attributable to climate change tripled globally, rising from 1.7 hours to 5.1 hours per person. As a result, climate change's share of global temperature-related sleep loss increased from 4.1% to 11.2% over the past five decades.

The report describes itself as the first global analysis to quantify climate change-driven sleep loss. It found that climate change has at least doubled temperature-related sleep loss in 1,335 of the 1,338 cities studied.

The analysis noted that hotter nights prevent the human body from recovering from daytime heat, increasing the risk of cardiovascular disease, stroke, mental health disorders, reduced productivity and other health complications.

Bangladesh is particularly vulnerable because of rapid urbanisation, the urban heat island effect and limited access to cooling, leaving millions exposed to increasingly warm nights, the report said.

It also highlighted that older adults, infants, pregnant women and low-income communities face the greatest risks, as limited access to cooling makes them more susceptible to disrupted sleep and its health consequences.

"Adults need seven to nine hours of sleep each night for optimal health. As climate change drives more frequent and intense hot nights, sleep disruption should be recognised as a growing public health concern," said Dr Courtney Howard, emergency physician, chair of the Global Climate and Health Alliance and president-elect of the Canadian Medical Association.

"These findings reinforce the need for adaptation measures that address inequities, alongside urgent reductions in greenhouse gas emissions to protect both health and prosperity," she added.

The report urged Bangladesh to incorporate nighttime heat risks into public health and climate adaptation planning. It recommended expanding access to cooling for vulnerable communities, redesigning cities to reduce urban heat, strengthening heat-health action plans and accelerating the transition away from fossil fuels.

It concluded that addressing climate-driven nighttime heat is essential not only to protect public health but also to safeguard productivity, educational outcomes and long-term economic resilience.