Controlled breaks as a fatigue countermeasure on the flight deck.
BACKGROUND
A major challenge for flight crews is the need to maintain vigilance during long, highly automated nighttime flights. No system currently exists to assist in managing alertness, and countermeasure options are limited. Surveys reveal many pilots use breaks as an in-flight countermeasure, but there have been no controlled studies of their effectiveness.


OBJECTIVE
We hypothesized that brief, regular breaks could improve alertness and performance during an overnight flight.


METHODS
A 6-h, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected.


RESULTS
During the latter part of the night, the treatment group showed significant reductions for 15 min post-break in slow eye movements, theta-band activity, and unintended sleep episodes compared with the control group. The treatment group reported significantly greater subjective alertness for up to 25 min post-break, with strongest effects near the time of the circadian trough. There was no evidence of objective vigilance performance improvement at 15-25 min post-break, with expected performance deterioration occurring due to elevated sleep drive and circadian time.


CONCLUSIONS
The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.
Neri
David F
DF
Fatigue Countermeasures Group, NASA Ames Research Center, Moffett Field, CA, USA. nerid@onr.navy.mil
Oyung
Raymond L
RL
Colletti
Laura M
LM
Mallis
Melissa M
MM
Tam
Patricia Y
PY
Dinges
David F
DF
D000328:Adult; D000337:Aerospace Medicine; D000704:Analysis of Variance; D004569:Electroencephalography; D004585:Electrooculography; D005221:Fatigue / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control* / Q000523:psychology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control* / Q000523:psychology; D016272:Occupational Health; D010561:Personnel Staffing and Scheduling / Q000458:organization & administration; D011597:Psychomotor Performance; D013997:Time Factors; D014851:Wakefulness; D014940:Work Schedule Tolerance / Q000502:physiology* / Q000523:psychology