01
Single-plotted actogram
Compact view of one day per row.
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.
3
protocol roles
4
control fields
4
reporting items
What this method is
An actogram is the standard visualization of circadian biology. Time of day runs along the x-axis, successive days stack down the y-axis, and activity is drawn as bar height or color intensity. For a nocturnal rodent the active band sits in the dark phase, and its shape over days reveals the clock.
A single-plotted actogram shows one 24 h period per row. A double-plotted actogram repeats each day so every row spans 48 h, which makes a period different from 24 h appear as a diagonal drift and makes phase shifts and free-running rhythms far easier to see. Double-plotting is the convention in rodent circadian work.
The plot is only as good as the activity series behind it. Bin a continuous activity measure (distance traveled per minute from video, wheel revolutions, or beam breaks) into 1, 5, or 10 minute bins, arrange the bins into a day-by-time matrix, annotate the light-dark schedule, and mark detected onsets.
- 01Endpoint
Start with the measured outcome
- 02Training role
Separate training from testing
- 03Workload
Define the exercise dose
- 04Apparatus
Match equipment to the protocol
- 05Reporting
Make replication fields visible
1
Endpoint
Start with the measured outcome
Decide whether the study is measuring adaptation, capacity, fatigue, metabolism, tissue response, recovery, or a downstream behavioral endpoint. The endpoint determines whether exercise is the intervention, the assessment, or both.
2
Training role
Separate training from testing
Training sessions deliver a repeated workload. Capacity, fatigue, exhaustion, or VO2peak sessions measure performance limits. Treating those roles as interchangeable makes the method harder to interpret.
3
Workload
Define the exercise dose
Record speed, incline, duration, frequency, progression rule, rest days, recovery timing, and total distance when relevant. The method name is not enough to reproduce the exposure.
4
Apparatus
Match equipment to the protocol
Treadmill lanes, belt calibration, incline range, cue method, metabolic integration, and tracking options all change what the method can support.
5
Reporting
Make replication fields visible
Report acclimation, animal factors, cue policy, completion rules, exclusions, stop criteria, and endpoint timing so another lab can reproduce the dose and judge interpretation limits.
How the protocol families differ
These are different method roles. Pick the row that matches the scientific question before setting speed, incline, duration, or endpoint timing.
| Protocol type | Purpose | Typical use | Watch for |
|---|---|---|---|
| Single-plotted actogram | Compact view of one day per row. | Quick screening of entrained activity under a light-dark cycle. | Free-running drift is hard to see across the row break. |
| Double-plotted actogram | Two days per row to expose rhythm shifts. | Free-running period, jet-lag, and phase-shift studies. | Each day appears twice; do not double-count activity. |
| Light-dark annotated actogram | Overlay white/black bars for the lighting schedule. | Showing entrainment relative to lights-off. | Keep the bar definition (ZT0/ZT12) explicit. |
Single-plotted actogram
- Purpose
- Compact view of one day per row.
- Typical use
- Quick screening of entrained activity under a light-dark cycle.
- Watch for
- Free-running drift is hard to see across the row break.
Double-plotted actogram
- Purpose
- Two days per row to expose rhythm shifts.
- Typical use
- Free-running period, jet-lag, and phase-shift studies.
- Watch for
- Each day appears twice; do not double-count activity.
Light-dark annotated actogram
- Purpose
- Overlay white/black bars for the lighting schedule.
- Typical use
- Showing entrainment relative to lights-off.
- Watch for
- Keep the bar definition (ZT0/ZT12) explicit.
Apparatus and settings that change the method
The same method label can describe very different experimental exposures. These settings should be visible before protocol selection.
Activity source
Video distance/min, wheel revolutions, infrared beam breaks, or telemetry.
Bin size
1, 5, or 10 min bins; smaller bins show detail, larger bins smooth noise.
Plot mode
Single (24 h/row) or double (48 h/row) plotting.
Lighting annotation
LD, DD, or LL bars and the ZT/CT reference.
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. 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. |
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.
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.
Reporting and interpretation checks
Use this section as the methods-record audit: caveats explain what can distort interpretation, and checklist fields make the workload reproducible.
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.
