Sleep and Performance Measures in Soldiers Undergoing Military Relevant Training

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Sleep and Performance Measures in Soldiers Undergoing Military Relevant Training
W.D. Killgore
A. Estrada
R.M. Wildzunas
T.J. Balkin


Inadequate sleep is known to impair a variety of
cognitive capacities, including attention, vigilance,
concentration. memory encoding, and some aspects of
higher order reasoning and judgment. The ability to
unobtrusively measure fatigue and predict its effects on
cognitive performance is vital to successful military
operations. Wrist actigraphy is one such method, but its
ability to accurately measure and predict performance in
militarily relevant activities is not well validated.
Healthy military volunteers (N = 108) were fitted with
wrist actigraphs (Actiwatch; Minimitter Inc.) while
undergoing one ofsix military education programs
lasting between 4 to 6 weeks. Sixty-four Actiwatches
were worn consistently and yielded valid data.
Actigraphic sleep data were analyzed with Actiware 3.41
using automated scoring algorithms. Indices ofsleep
duration, latency, and quality were used to predict
academic success in these courses. Averaging across all
courses and volunteers, Soldiers obtained 5.8 hours of
sleep per night (SD = 0.5). Sleep duration was typically
reduced to 4.6 (SD = 1.5) hours the night preceding an
exam. Regardless of course type or test content,
academic performance was significantly predicted by
total sleep time (48 hours before, r =.60, p < .00 I; 24
hours before, r = .54,P < .00 I), sleep latency (48 hours
before, r = -.46, p = .002; 24 hours before, r = -.46, p =
.002), number of immobile minutes (48 hours before, r=
.58, p < .00 I; 24 hours before, r = .52, p = .00 I), and
fragmentation index (48 hours before, r = .29, p = .05; 24
hours before, r = .28, p =.05), but not total activity level
(48 hours before, r = .06, ns; 24 hours before, r = .07,
ns). Regardless ofcourse or exam content, academic
performance was significantly related to the amount and
quality of sleep obtained within the 48-hour period
preceding the exams. Actigraphy appears to be a valid
and unobtrusive method for predicting academic
performance in military courses, although issues of
participant compliance and detection of off-wrist periods
need to be improved.