The Study
Association between night shift work and markers of metabolism, cardiovascular and immune system in a population-based German cohort
This study looked at people who worked nights and people who didn’t, and checked if they had different health numbers — like cholesterol or weight. It found mostly no big differences, but it didn’t prove that working nights causes those health things — it just saw if they happened together.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
This study looked at people who worked nights and compared them to people who only worked during the day to see if nights made them sicker.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The HDL drop in women is small and within normal range; no major health risks were found for night workers overall.
- 2People who worked nights had the same BMI, blood pressure, sugar, and cholesterol as day workers—except women who worked nights had slightly lower 'good' cholesterol (HDL).
- 3Men who used to work nights had slightly lower red blood cells; women had slightly higher ones—but all were still normal.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
GeroScience
Year
2025
Authors
Nora Bittner, Horst-Werner Korf, S. Moebus, Börge Schmidt, Svenja Caspers
Related Content
Claims (5)
Working irregular hours or not sleeping well can mess up your body’s internal clock, which in turn hurts your metabolism and liver — making it harder for your body to process food and stay healthy.
People who work nights don’t seem to have worse health markers like weight, blood pressure, or blood sugar compared to similar people who only work days—so night shifts probably don’t mess up your metabolism, heart, or immune system in this group of Germans.
People who used to work nights don’t seem to have more health problems like diabetes or heart disease risks later on than people who never worked nights—even when you account for their age and medicines they take.
Working nights might affect your health differently depending on things like your gender, when you naturally feel awake or sleepy, or how much money you make — but this study didn’t check any of those things, so we can’t fully explain why other studies have found different results.
Women who work nights might have lower levels of the 'good' cholesterol than women who work during the day, but this doesn’t seem to happen in men—so night shifts might affect women’s cholesterol differently.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.