Table 1.

Inclusion and exclusion criteria for reviewed studies.

375	Reviewed
278	Excluded
	26	24 h or Holter monitor study
	6	Animal
	1	Duplicate record in database
	11	Elderly, geriatric, or palliative sample
	7	Elite or high level athletes
	86	Exclusive to patient population
	1	Incorrect calendar year (i.e., published 2013)
	32	Infant, child or teenage sample
	50	Letter, review, commentary, etc.
	23	No resting baseline given
	17	Non-linear, non-standard, etc. measures
	13	Time domain measures only
	5	Unavailable at the time of review
97	Included
	97	Met criteria
	3	Multiple or duplicate usable records