provide some means of benchmarking the components of Baby-Lag and objectively
assessing the range of variability that is reported from parent to parent.
Subjective Methods for Assessing Tiredness/Sleepiness
and Fatigue: Can We Subjectively Measure the Experience
of Parental Sleep Loss, Tiredness, and Fatigue?
While the majority of parents technically experience only tiredness/sleepiness rather
than true fatigue, when the latter is manifested it generally involves underlying
organic causes such as physical illness or depression. Recovery from traumatic or
operative childbirth might provide the relevant conditions for fatigue, as might a
prolonged inability to adequately relieve sleep pressure experienced as a conse-
quence of repeated sleep disturbance. Such conditions suggest that the phenomenon
of Baby-Lag is one area where tiredness and fatigue may be mutually reinforcing.
Many psychometric tests and scales have been developed that attempt to capture
individual experience or awareness of tiredness/sleepiness. Well-known examples
used in clinical settings are presented as a standardized series of questions com-
prising a clinically validated scale or score, such as the Epworth Sleepiness Scale
and the Pittsburgh Sleep Quality Index. Some of these have been (inappropriately)
applied to healthy participants in previous studies of parental tiredness (see below).
A review of the literature on parental sleep in the postpartum period reveals that
use of subjective measures of tiredness and fatigue with parents during the post-
partum period is common, but few if any tools have been designed with this
population in mind. A great number of subjective measures of sleep loss, sleep
disturbance, tiredness, and fatigue have been applied. Broad categories of assess-
ment include single-point assessments, which obtain a response to a single yes or no
question; one-dimensional ratings, which ask subjects to evaluate their tiredness or
fatigue on a single scale; and multidimensional ratings, which combine responses to
a set of interrelated scales to form a corporate measure of tiredness or fatigue
(Milligan et al. 1997 ). Perceived sleep estimates, of a simple form and in the form
of sleep diaries are also widely used. The following section will describe the scales
and estimates that have been applied to sleep, tiredness, and fatigue in the post-
partum period.
Visual Analog Scales (VAS) have been widely used to measure
sleep/tiredness/fatigue. A VAS uses a simple 100-mm line, presented with
anchoring words or statements at each end point. Respondents are asked to place a
mark at the point on the line between the two words or statements that best rep-
resents their experience. The researcher then measures the distance from one end of
the line to the respondent’s mark to obtain their score or rating. By obtaining the
score in this way, respondent’s ratings are continuous and precise, in contrast to
ordinal ranked Likert scale responses that force the respondent to choose a ranking
category (Snyderhalpern and Verran 1987 ).
3 Baby-Lag: Methods for Assessing Parental Tiredness and Fatigue 35