Measurement notes
Record continuous food and water events, define a meal by a minimum size and an inter-meal interval, and summarize timing, frequency, size, and the proportion of intake in the dark phase. Several stable days are averaged.
Endpoint methods library
Circadian & activity rhythm endpoint
Feeding and drinking rhythm
Daily timing and distribution of food and water intake, including meal timing, frequency, and the dark/light intake ratio.
Unit
meals/day, grams or mL, dark/light ratio
Readout
Meal timing, meal frequency and size, and dark/light intake ratio
Assays
Home-cage feeders, lickometers, metabolic cages, video
Decision summary
Use feeding and drinking rhythms when the question is when, not just how much, the animal consumes. The clock concentrates intake in the dark phase in healthy nocturnal rodents, and a shift toward light-phase eating is an early marker of circadian-metabolic disruption that locomotor activity alone can miss.
| Primary value | Meal timing, meal frequency and size, and dark/light intake ratio |
|---|---|
| Common units | Meals per day, grams or mL per phase, percent intake in dark |
| Compatible assays | Home-cage feeders, lickometers, metabolic cages, video |
| Required boundary | Meal definition (minimum size, inter-meal interval) and phase windows |
| Do not infer alone | Total energy balance or metabolic rate |
Interpretation limit
Intake timing reflects both the clock and homeostatic hunger, so a shifted feeding rhythm should be read alongside body weight, activity, and, where available, energy expenditure rather than as a pure clock readout.
Data capture
Store animal ID, meal definition, phase windows, meal counts and sizes, dark/light intake, and days averaged.
Confound checks
- Spillage or grooming at the feeder misread as intake.
- Single vs group housing changing intake patterns.
- Diet palatability and restriction protocols.
- Scheduled feeding overriding the endogenous pattern.
Reporting checklist
- Meal definition and phase windows.
- Food and water measurement method.
- Days averaged and housing condition.
- Companion measures (body weight, activity, metabolic rate).
References
Evidence notes
Endpoint pages should cite the method literature behind the scored value and keep high-specificity protocol claims qualified unless the source supports them.
- Jud C et al. A guideline for analyzing circadian wheel-running behavior in rodents under different lighting conditions. Biol Proced Online. 2005. doi:10.1251/bpo109.
- Refinetti R, Cornélissen G, Halberg F. Procedures for numerical analysis of circadian rhythms. Biol Rhythm Res. 2007. doi:10.1080/09291010600903692.
Related workflow paths
Endpoint articles link to adjacent products, software workflows, and sibling endpoints where the connection is useful and already routable.
