ActiLife software generates activity counts from data collected by Actigraph accelerometers <https://s3.amazonaws.com/actigraphcorp.com/wp-content/uploads/2017/11/26205758/ActiGraph-White-Paper_What-is-a-Count_.pdf>.
  Actigraph is one of the most common research-grade accelerometers. There is considerable research
  validating and developing algorithms for human activity using ActiLife counts. Unfortunately,
  ActiLife counts are proprietary and difficult to implement if researchers use different accelerometer brands.
  The code  creates ActiLife counts from raw acceleration data for different accelerometer brands and it is developed
  based on the study done by Brond and others (2017) <doi:10.1249/MSS.0000000000001344>.

Reads raw 'accelerometry' from 'GT3X+' data and 
    plain table data to calculate Activity Index from 'Bai et al.' (2016)
    <doi:10.1371/journal.pone.0160644>.  The Activity Index refers to the 
    square root of the second-level average variance of the three
    'accelerometry' axes.

Contains functions to generate pre-defined summary statistics from activPAL
    events files <https://www.palt.com/>.  The package also contains functions to produce informative 
    graphics that visualise physical activity behaviour and trends.  This includes
    generating graphs that align physical activity behaviour with additional time based 
    observations described by other data sets, such as sleep diaries and continuous glucose 
    monitoring data.

Contains data and functions that can be used to make 
  actuarial life tables. Each function adds a column to the inputted dataset for
  each intermediate calculation between mortality rate and life expectancy. Users can 
  run any of our functions to complete the life table until that step, or run
  lifetable() to output a full life table that can be customized to remove optional columns. 
  Methods for creating lifetables are as described in Zedstatistics (2021) <https://www.youtube.com/watch?v=Dfe59glNXAQ>.

Read in activity measurements from standard file formats
  used by circadian rhythm researchers, currently only 'ClockLab' format,
  and process and plot the data.  The central type of plot is the actogram,
  as first described by in "Activity and distribution of certain wild mice 
  in relation to biotic communities" by MS Johnson (1926) <doi:10.2307/1373575>.