Adults had higher nighttime output of a protein breakdown marker
Among 859 adults, the mean daytime-to-nighttime ratio of hourly urinary urea output was below 1, indicating greater nighttime output.
Limit: Only one 24-hour collection per participant limits assessment of day-to-day variation in urea output
Edited by Boris Djordjevic · AgingResearch.News
In a cross-sectional observational study, 859 adults aged 18 or older in Italian-speaking Switzerland provided separate daytime and nighttime urine collections over 24 hours. The group included 484 women and had a mean age of 50.1 years. Researchers compared hourly daytime and nighttime output of urea, a marker of protein breakdown.
Urea output was generally higher at night. Women under 40 had nearly equal daytime and nighttime rates, while women over 65 showed a more pronounced nighttime predominance. No comparable age-related trend appeared in men. In an analysis accounting for several other factors, older age, larger overnight blood pressure drops and higher urinary sodium output were independently associated with the daytime-to-nighttime ratio.
Why it matters
The authors suggested that the findings could inform strategies for timing nutrition to help preserve muscle health across the lifespan.
Caveats
The cross-sectional design cannot establish cause and effect, and urinary urea is a proxy for protein breakdown, not a direct measure of muscle loss. Each participant provided only one 24-hour collection.
- Amino acid metabolism
- Circadian clock
- Day-to-night urea excretion ratio
- Nocturnal blood pressure dipping
- Urinary sodium excretion
- Humans
The paper
Circadian Modulation of Protein Catabolism: Insight from a Population Study
Università della Svizzera italiana; Ente Ospedaliero Cantonale
Nutrients, May 17, 2026, Open access
