Table 3 Parameters reported in studies of Rest–Activity Rhythms: additional details
Cosinor model (parametric) | |
Midline estimating statistic of rhythm (MESOR) | Estimates the arithmetic mean of the values throughout the 24-h period |
 Amplitude | Distance from the rhythmic mean to the peak or trough of a mathematical model |
 Acrophase | Time interval during which the highest values are expected |
Nonparametric approach | |
 Interdaily stability | Quantifies the degree of resemblance between the activity patterns on individual days; ranges from 0 to 1 and may typically be about 0.6 for healthy adults |
 Intradaily Variability | Quantifies the fragmentation of periods of rest and activity; ranges from 0 to 2 and typically is < 1 for healthy adults, with higher values indicating a more fragmented rhythm |
 L5 | Average of the activity values for the 5 least active consecutive hours in the 24-h cycle |
 L5 Onset | Onset time of the five most restful consecutive hours |
 M10 | Average of the activity values for the 10 most active consecutive hours in the 24-h cycle |
 M10 Onset | Onset time of the 10 most active consecutive hours |
 Amplitude | Difference between M10 and L5 |
 Relative Amplitude | Calculated by dividing AMP by the sum of L5 and M10; ranges from 0 to 1, with higher values indicating higher amplitude of the rhythm |
Sleep quantity analysis (reported as Individual Mean values or Intra-Individual Variability e.g. SD, RMSSD) | |
 Time in bed (TIB) (Lights Off (LO)) | Difference between the get-up time and bedtime (Lights Off: time bedroom lights are turned off is reported in some therapy studies) |
 Total sleep time (TST) | Duration of the sleep episode, calculated on the actual time of sleep start and sleep end |
 Sleep latency (SOL) | Difference between time in bed and the actual time the monitored subject starts sleeping |
 Mean activity (MA) | Number of movements within specified epoch (usually 1 min) |
 Number of awakenings longer than 5 min (NA > 5) | Number of awakenings longer than 5 min |
 Wake after sleep onset (WASO) | Wake time (min) after sleep onset |
 Sleep efficiency (SE %) | Percentage of effective sleep during time in bed |
 Fragmentation Index (FI %) | % of sleep continuity/discontinuity. It is calculated as the amount of time associated with movement (restlessness) during the sleep period expressed as a percentage |
Putative Circadian Phase Measures (derived from Sleep quantity analysis data) | |
 Sleep Onset | Time is the clock time (HH:MM) of the first epoch scored as sleep in each main rest interval |
 Sleep Offset | Mean sleep offset time is the clock time (HH:MM) of the last epoch scored as sleep in each main rest interval |
 Sleep midpoint | Calculated as the midpoint between sleep onset and sleep offset |
 Sleep Regularity Index (SRI) | This is defined as the percentage probability of a person being asleep (or awake) at any two time points 24 h apart |