pyActigraphy.sleep.ScoringMixin.SleepMidPoint

ScoringMixin.SleepMidPoint(freq='15min', bin_threshold=None, to_td=True, algo='Roenneberg', *args, **kwargs)

Sleep midpoint

Center of the mean sleep periods

Parameters:

• freq (str, optional) – Resampling frequency. Default is ‘15min’

• bin_threshold (bool, optional) – If bin_threshold is not set to None, scoring data above this threshold are set to 1 and to 0 otherwise. Default is None.

• to_td (bool, optional) – If set to true, the sleep midpoint is returned as a Timedelta. Otherwise, it represents the number of minutes since midnight.

• algo (str, optional) – Sleep scoring algorithm to use. Default is ‘Roenneberg’.

• *args – Variable length argument list passed to the scoring algorithm.

• **kwargs – Arbitrary keyword arguements passed to the scoring algorithm.

Returns:

smp

Return type:

float or Timedelta

Notes

Sleep midpoint (SMP) is an index of sleep timing and is calculated as the following [1]:

\[SMP = \frac{1440}{2\pi} arctan2\left( \sum_{j=1}^M\sum_{i=1}^N s_{i,j} \times sin\left(\frac{2\pi t_i}{1440}\right), \sum_{j=1}^M\sum_{i=1}^N s_{i,j} \times cos\left(\frac{2\pi t_i}{1440}\right) \right)\]

with:

• \(t_j\), time of day in minutes at epoch j,

• \(\delta(s_{i,j}, s_{i+1,j}) = 1\) if \(s_{i,j} = s_{i+1,j}\) and 0 otherwise.

References

[1]

Lunsford-Avery, J. R., Engelhard, M. M., Navar, A. M., & Kollins, S. H. (2018). Validation of the Sleep Regularity Index in Older Adults and Associations with Cardiometabolic Risk. Scientific Reports, 8(1), 14158. https://doi.org/10.1038/s41598-018-32402-5

Examples