Caffeine maintains vigilance and improves run times during night operations for Special Forces.
OBJECTIVE
This study examined the effects of caffeine (CAF) on vigilance, marksmanship, and run performance during 27 h of sustained wakefulness in Special Forces personnel.


METHODS
There were 31 soldiers (29.8 +/- 5.4 yr, 86.4 +/- 8.6 kg) who were divided into placebo (PLAC, n = 15) and CAF (n = 16) groups. A 6.3-km control run was completed on the morning of Day 1. In the evening of Day 2, soldiers performed a control observation and reconnaissance vigilance task (ORVT) in the field. This 90-min task was repeated twice more between 02:00 and 06:00 on Day 3 during an overnight period of sleep deprivation. Marksmanship was assessed before and after the ORVT. PLAC or 200 mg of CAF gum was administered at 01:45, 03:45, and approximately 06:30 on Day 3. A final 6.3-km run commenced within 30 min of receiving the final dose.


RESULTS
ORVT was maintained in CAF at control levels of 77 +/- 13% during the overnight testing. However, values decreased significantly for PLAC from 77 +/- 15% to 54 +/- 29% and 51 +/- 31% during the first and second overnight testing periods, respectively. CAF had no effect on marksmanship but improved 6.3-km run times by 1.2 +/- 1.8 min. Run times slowed for PLAC by 0.9 +/- 0.8 min from approximately 35 min during the control run; the changes in performance were significant between groups.


CONCLUSIONS
It was concluded that CAF maintained vigilance and improved running performance during an overnight field operation for Special Forces personnel.
McLellan
Tom M
TM
DRDC Toronto, Toronto, ON, Canada. tom.mclellan@drdc-rddc.gc.ca
Kamimori
Gary H
GH
Voss
David M
DM
Bell
Douglas G
DG
Cole
Karl G
KG
Johnson
Dagny
D
D000328:Adult; D002110:Caffeine / Q000008:administration & dosage* / Q000494:pharmacology; D002940:Circadian Rhythm / Q000187:drug effects*; D005389:Firearms; D006801:Humans; D008297:Male; D008887:Military Medicine; D008889:Military Personnel; D009520:New Zealand; D011446:Prospective Studies; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D012420:Running / Q000502:physiology*; D012892:Sleep Deprivation / Q000503:physiopathology; D013997:Time Factors; D014851:Wakefulness / Q000187:drug effects / Q000502:physiology*
D002110:Caffeine