Effects of exercise, bedrest and napping on performance decrement during 40 hours.

Voung malt' N.n.il vulunlrtrs vtere dcnird unrmiil IHK lunidl slet-p and maintained on a 60-min Inalnn ill IM» min leslin|> schrdulr during 40 cunserulive hrs. Ten subjects bicycled, 20 subjects controlled lit. activity during bedrest. and 10 subjects napped. Kight measures of addition, auditor) vigilance, mood, and oral temperature were obtained. The Bedrest group showed significant impairment on all eight measures, and thus, gave no support to the foreed-rest theory of sleep function. The Kxercise group was worse than the Nap and Bedrest groups for all measures. In spite of fragmented, reduced sleep (about 3.7 hrs per 24 hrs), the Nap group had no impairment on six of tin measures. I In results suggest that exercise increases ihe impairment due to sleep loss, and aaps reduce or remove tnis impairment. Bedrest is not a substitute for sleep. OKSCRIFIOHS: Sleep loss. Performance, Mood, Naps, Kxercise. The purposes of this study were to answer two empirieal questions and to test the JoneJ-rcst theof) ot sleep funetion. Tl;c empirieal questions were: (I) Do naps prevent sleep loss deerement in perlomianee when subjeets are deprived of normal nocturnal sleep.' (2) Does exercise increase or decrease the impairment of performance and mood during sleep loss' An early version of the forecd-rest theory of sleep function has been traced back to Claparede (I9Ü.'>) by Webb (1974): "It is noi Seeause we are intoxicated orexhausted that we sleep: instead we sleep in order to not he that way ■' (translation by Webb and Lubin). In Webb's version, (he primary postulate is that survival requires periods of non-respondinj;. Sleep is an active process which prevents the organism from responding when predator-prey relationships make activity dangerous, or when foraging for food would be inefficient. The existence of This MWck ».is supported h\ ihf Adsaiucil Rcscarih Pni| ctts Agi-no of Ihe IVpanmrnl of IX-fcnsc under Order No |S%, and tn Ihe [Vp.mmenl of ihe Navy. Bureau of Medicine and Surgcn. under Work L'nil M4.W 07 .♦008DACJ The views and eonclusions contained herein are thotc of ihe aulhors and stwmld noi he nlerpreled as ncecssanly refleeling ihe official poliues. either expecued or nnplied. ot ihe Defense Advanced Research Hroiecls Ageiicv ihe IXpanmcnl of Ihe Navy, or ihe U S. Govcmmeni Phe aulhors Ihank Julie MOMS. Bill Jensm.i R;iv Hilhcrt. Don Irwin. Marion Auslm. Kom (ireenc. (iary Mimell. and Mall Sinclair for assistance in Ihe planning and eteculion ot ihis slud. Address requesls for rcprmls lo Ardie l.uhin. Ph D . Naval Heailh Research ( enler. San Diego. ( alitorma >2\*'2 both hibernation and estivation among aMmals lends evidence to the supposition that a decrease in metabolic rate at appropriate limes is an important survival mechanism The forced-rest theory denies that the primary function of sleep is restorative (Webb, 1974). Zepelin and Rechlsc halfen (1974) regard it as a fact that: "slejp in effect se's a ceiling on metabolic expendituies by limiting the amount of lime available for activity The enforcement of rest... appears to be the principal contribution that sleep makes in the regulation of energy expenditure |p 4541"' Due lo the failure to isolate hypothesized somnotoxins. Berger, Taub, and Walker! 1973) also have espoused the forced-rest theory of sleep func lion. Thf simple vi-rsion of the forced-rest iheon makes sleep unnecessary when the subject remains quiet in bed. The common-sense view ol napping is that it benefits and refreshes any subje i who is suflenng from sleep loss and/or fatigue. But the substitution of scheduled naps for monophasic nocturnal sleep disrupts the usual sleep/wake pattern. Two studies have concluded that any alteration in established sleep patterns, even an increase in the not mal amount of sleep, is deleterious to performance and mood (Taub & Beiger. 1974a, 1974b). Ihe common-sense view of exercise is that it provides a short-term arousal from sleep 1 iss but continued exercise combined with sleep loss leads to protound deterioration in IVKHKI and ptffanMMC Yel Ihe only published study to date concluded lhal during sleep loss the effect of exercise was no difler