Sleep

Seasonal and geographic variation in sleep duration among U.S. adults: Evidence from the 2022 BRFSS.

DelRosso L & Vodapally M • Chronobiology international • 2026

PubMed 41521946 DOI 10.1080/07420528.2025.2611866

TL;DR

Geographic context, particularly time zone and latitude, plays a more consistent role than seasonality in shaping sleep duration in the U.S.

Key Findings

Results

The overall mean self-reported sleep duration among U.S. adults in 2022 was 7.96 hours.

Data were drawn from the 2022 Behavioral Risk Factor Surveillance System (BRFSS)
Sample included 416,731 adults representing a weighted population of approximately 259 million
Complex survey weights and general linear models adjusted for age and sex were used
Sleep duration was self-reported

Results

Monthly variation in sleep duration was modest and largely not statistically significant.

Monthly averages ranged from 7.82 hours in April to 8.13 hours in January
The range across months was approximately 0.31 hours
The month × latitude interaction was not significant
Effect sizes were small (ηp² range = 0.00002–0.00080)

Results

Sleep duration varied significantly by time zone, with Pacific zone respondents reporting the longest sleep and Mountain and Hawaii time zones reporting the shortest.

Pacific time zone respondents reported the longest sleep at 8.37–8.56 hours
Mountain and Hawaii time zone respondents reported the shortest sleep at approximately 7.0–7.5 hours
Effect sizes were small across all models (ηp² range = 0.00002–0.00080)
Geographic differences were described as 'modest but consistent'

Results

Adults in southern states reported consistently longer sleep than those in northern states.

Latitude-based differences were statistically significant
Cohen's d for latitude was 0.23, indicating a small effect size
The month × latitude interaction was not significant
Southern versus northern differences were described as 'consistent' geographic differences

Results

Men slept less than women, and older adults reported slightly longer sleep.

Sex and age were included as covariates in the general linear models
These findings are consistent with previously described demographic patterns in sleep duration
Models were adjusted for both age and sex
Effect sizes across all models were small (ηp² range = 0.00002–0.00080)

What This Means

This research suggests that where you live in the United States has a more consistent influence on how long you sleep than the time of year. Using data from over 416,000 American adults surveyed in 2022, researchers found that people in the Pacific time zone sleep the longest (averaging about 8.4–8.6 hours), while those in the Mountain and Hawaii time zones sleep the least (around 7.0–7.5 hours). People in southern states also tended to sleep longer than those in northern states. By contrast, sleep duration did not change much from month to month throughout the year, ranging only about 18 minutes between the lowest month (April) and highest month (January). The study also found that men reported sleeping less than women, and older adults reported sleeping slightly more. However, all of the differences found — whether by time zone, latitude, season, or demographics — were statistically small in magnitude, meaning that while the patterns are real and consistent, they do not represent dramatic differences in sleep across groups. This research suggests that environmental and geographic factors tied to time zones and latitude (which may relate to light exposure, social schedules, and local culture) shape sleep habits more powerfully than the changing seasons. Understanding these geographic patterns could help public health efforts target communities where sleep duration tends to be shorter, potentially informing policies around time zone boundaries, daylight exposure, and regional sleep health initiatives.

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Citation

DelRosso L, Vodapally M. (2026). Seasonal and geographic variation in sleep duration among U.S. adults: Evidence from the 2022 BRFSS.. Chronobiology international. https://doi.org/10.1080/07420528.2025.2611866

Key Findings

What This Means

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