Typically, teams deprive themselves of rest and sleep an average of two to six hours per day. Teams that sleep the least gain the most distance in time and space, provided they stay on course and don't make a wrong turn (only few degrees off early-on means going further than the straight-line distance to the next checkpoint). Sleep deprivation imposes an intoxicating influence on the mind, creating psycho-behavioral deficits, reducing short-term memory, slowing down mental processing, and creating perceptual distortions and hallucinations.

Accurate navigation from point-to-point while using multiple means of travel demands exceptional concentration for a successful Eco-Challenge performance.

But here lies one of the largest obstacles: humans deprived of 24 hours sleep have a reaction similar to intoxication at a .07% blood alcohol level - just like a 150 lb. male who has chugged 3 beers in 60 minutes![1] That alone will hamper navigational accuracy, and certainly wreak havoc with someone trying to find the way in a previously unknown tropical rain forest in an inebriated state.

But there's more. When an athlete follows acute 2-4 hour temporal shifts of habitual sleep periods, psycho-behavioral deficits have been observed to result from selective sleep stage deprivation (REM and/or stage 4), as real, live mental deficit consequences.[2] How do you spell borderline insanity?

No, that's not all. 'Recognition performance' is also impaired when observed subjects lose only 24 hours of sleep. Sleep deprivation increases occurrence of lapses, periods of lowered reaction times especially right after waking, with noticeable loss in short-term memory.[3]

Yet nighttime is even worse. Human mental processing actually slows down during the night hours. Eighteen healthy young adults - during 36 hours of constant wakeful bed rest - required extra mental processing to generate barely a normal reaction time at night.[4]

Just imagine competing in an adventure race, attempting to traverse a 300-mile course in less than two weeks time, in an exhausted physical state. Sleep loss affects each of us differently. Going without it may contribute to motor and behavioral abnormalities linked to a REM sleep behavior disorder.

Intrusions of one state of being (wakefulness, non-REM sleep, and REM sleep) into another have been reported in mixed, poorly defined, or only partially developed states. Dissociation of states may be responsible for confusion arousal, hallucinations, and cataplexy. [5]

On top of all this, competitors are taken captive by perceptual distortions and hallucinations during the course of sleep deprivation. Subjects deprived of only 48 or 72 hours without sleep experience visual task-related perceptual distortions and hallucinations. Perceptual distortions are the most frequent in the late night-early morning hours[4 AM] and least frequent in the late afternoon-early evening hours[4:00-8:00 PM].[6]

With the mind craving sleep - reeling to and from like a drunken sailor trying to navigate with a sure and true hand - direction may escape the mind for a moment while distance is ever plodded, resolved with each step. "The next checkpoint has got to be around here...somewhere!"

REFERENCES [1]-Impairment of driving performance caused by sleep deprivation or alcohol: a comparative study, Fairclough SH, Graham R, Hum Factors 1999 Mar 41:1 118-28.
[2]-Behavioral and psychophysiological correlates of irregularity in chronic sleep routines. Taub JM, Biol Psychol 1978 Sep 7:1-2 37-53.
[3]-Effects of sleep deprivation on short-term recognition memory. Polzella DJ, J Exp Psychol [Hum Learn] 1975 Mar 104:2 194-200.
[4]-Speed of mental processing in the middle of the night. Monk TH, Carrier J, Sleep 1997 Jun 20:6 399-401.
[5]-Update on disorders of sleep and the sleep--wake cycle. Culebras A, Psychiatr Clin North Am 1992 Jun 15:2 467-89.
[6]-Perceptual distortions and hallucinations reported during the course of sleep deprivation, Babkoff H, Sing HC, Thorne DR, Genser SG, Hegge FW, Percept Mot Skills 1989 Jun 68:3 Pt 1 787-98.