Use when
- You need to see activity onset, free-running drift, or a phase shift directly.
- You are screening entrainment to a light-dark cycle or a jet-lag protocol.
- You want to sanity-check a periodogram or cosinor fit against the raw pattern.
Research Methods
Method
Actogram generation and interpretation
An actogram plots successive days of activity in stacked rows so circadian researchers can read activity onset, period, entrainment, and rhythm stability at a glance. Single-plotted shows one 24 h day per row; double-plotted shows 48 h per row and is the standard for spotting free-running drift.
Decision summary
Build a double-plotted, light-dark-annotated actogram whenever you need to see circadian phase, period, and stability rather than a single summary number. A single-plotted actogram shows one 24 h day per row; a double-plotted actogram repeats each day so every row spans 48 h, turning a non-24 h period into a visible diagonal drift. It is the visual companion to the numeric endpoints (onset, period, amplitude) and the first thing to inspect before trusting any periodogram.
| Axes | Time of day on x, successive days stacked on y. |
|---|---|
| Plot mode | Single (24 h/row) or double (48 h/row). |
| Activity encoding | Bar height or color intensity per bin. |
| Annotation | Light-dark bars and detected onset markers. |
Do not use when
- You only need a single scalar endpoint for statistics (use the periodogram or nonparametric indices).
- The record is too short (a few days) to show day-to-day structure.
Caveats
- Bin size changes the visual texture; keep it fixed across animals being compared.
- Masking by light can make onset look sharper than the underlying clock.
- A double-plotted actogram repeats each day, which can confuse activity totals.
- Actograms are qualitative; pair them with numeric endpoints for statistics.
Reporting checklist
- Single vs double-plotted and the time reference (ZT or CT).
- Activity measure and bin size.
- Lighting schedule and how light-dark bars are defined.
- Onset-detection rule if onsets are marked.
References
Jud C et al. 2005. A guideline for analyzing circadian wheel-running behavior in rodents under different lighting conditions.
Practical guide to actogram construction and reading under LD, DD, and LL.
https://doi.org/10.1251/bpo109
Pittendrigh CS, Daan S. 1976. A functional analysis of circadian pacemakers in nocturnal rodents.
Foundational analysis of onset, period, and entrainment in rodent actograms.
https://doi.org/10.1007/BF01417856
Refinetti R, Cornélissen G, Halberg F. 2007. Procedures for numerical analysis of circadian rhythms.
Numeric methods that complement the visual actogram.
https://doi.org/10.1080/09291010600903692
Related surfaces
Use these related surfaces to move from the scientific method question to the relevant product page, endpoint definition, analysis tool, or adjacent guide.
ConductPhenotype
Generates double-plotted actograms from home-cage video.
Periodogram (method)
The numeric period-detection companion to the actogram.
Activity onset (endpoint)
The phase marker read off the actogram’s leading edge.
Free-running period (endpoint)
The tau that actogram drift reveals under constant darkness.
