mood effects in conjunction with posture and location of measurement on the blood
pressures of a sample of hypertensive women (data from James et al. 1988 ). The
effect sizes shown (height of the bars) are based on z-scores calculated from each
subject’s 24-h mean pressure and the standard deviation of that mean, and represent
the number of mmHg from the 24-h mean of a person who had a 24-h standard
deviation of 10. Since the effect sizes are tied to the magnitude of standard devi-
ation, the magnitude of the effects will increase or decrease as the 24-h standard
deviation varies (James 2013 ).
As illustrated in thefigure, the size of the estimated blood pressure adjustments
associated with the mix of ecological momentary factors varies considerably.
A closer examination of the specific effects of each of the parameters shows that
they are more or less additive with regard to blood pressure variation (James 2013 ).
Each set of factor alternatives defines a momentary state. By simple subtraction, it is
easy to calculate that the allostatic change in pressure from one state to another can
be substantial. Because a change in habitus from sitting to standing, or a mood
change from happy to angry could happen almost instantly, it is clear that the
allostatic change that defines the“hidden adaptability”of blood pressure is an
instantaneous process (James 2013 ).
Fig. 8.5 Exemplar effects of various reported activities on daily blood pressure (data from James
and Pickering 1991 ). Defined as mmHg from the 24-h mean and is based on the assumption that
the measure of dispersion around the 24-h mean (standard deviation) is 10 (modified from James
2013 )
156 G.D. James