Among 360 middle-aged and older Japanese community dwellers, low actigraphy-measured sleep efficiency was associated with psychological distress only in working women, with no evidence of a relationship in men (working or not) or non-working women.
Key Findings
Results
Lower objectively measured sleep efficiency was associated with higher psychological distress only among working women.
After adjustment for confounders, psychological distress (high K6 group) was associated with low sleep efficiency in working women (β = -0.060, p = 0.013).
Sleep efficiency was measured with actigraphy (MTI-220, ACOS Co., Ltd.), and psychological distress with the Kessler 6 scale (K6).
Analysis used multiple logistic regression with the high K6 group as the objective variable, stratified by work status and sex.
Results
No evidence of an association between sleep efficiency and psychological distress was found in working men, non-working men, or non-working women.
The abstract states 'We found no evidence of a relationship between other indicators of psychological distress in men with or without work and women without work.'
Analyses were stratified by sex and work status, giving four subgroups.
Methods
The study sample comprised 360 community-dwelling middle-aged and older adults in Shika-machi, Ishikawa, Japan, with a majority of women.
Women made up 54.4% of participants.
Mean age was 63.09 ± 10.48 years; the age range of the eligible population was 40–90 years.
Data were collected in a cross-sectional design between January 2018 and April 2020.
Conclusions
The authors interpret the findings as suggesting that work combined with poor sleep efficiency may be associated with greater psychological distress in middle-aged and older women.
The association was specific to the working women subgroup.
The authors call for longitudinal studies of sleep efficiency and psychological distress in middle-aged and older women that consider work-related effects.
The cross-sectional design does not allow determination of causal direction.
What This Means
This study looked at whether sleeping less efficiently (spending less of the time in bed actually asleep) is linked to feeling psychologically distressed, such as anxious or low in mood, among 360 adults aged 40 to 90 in a Japanese town. Sleep was measured objectively with a wrist-worn activity monitor rather than by self-report, and distress was measured with a short questionnaire (the K6). The researchers looked separately at men and women, and at people who did and did not work.
They found that lower sleep efficiency was linked to greater psychological distress only among women who were working. No link was found for working men, non-working men, or non-working women. This suggests that the relationship between sleep and distress may differ by sex and by work status, and that work may play a role for women in this age group.
Because the study measured people at a single point in time, it cannot show whether poor sleep leads to distress, distress leads to poor sleep, or something else drives both. The sample was also fairly small once split into subgroups. The authors recommend longer-term studies that follow people over time and take work-related factors into account.
Check Your Own Numbers
Upload your bloodwork. We'll cross-reference your results against this study and 4,700 others.
Sato K, Tsujiguchi H, Miyagi S, Morita E, Suzuki F, Hara A, et al.. (2026). Relationship between objective sleep efficiency and psychological distress in middle-aged and older Japanese: Results by work in the Shika study.. BMC psychology. https://doi.org/10.1186/s40359-026-05656-2