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Neuroscience Letters 516 (2012) 177– 181

Contents lists available at SciVerse ScienceDirect

Neuroscience Letters

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orking hours, sleep, salivary cortisol, fatigue and neuro-behavior during Marsnalog mission: Five crews study

alwant Raia,b,∗,1, Bernard H. Foinga, Jasdeep Kaura,b

Faculty of Earth & Life Sciences, Vrije Universiteit Amsterdam & ILEWG, Amsterdam, The NetherlandsJBR Institute of Health Education Research & Technology, India

r t i c l e i n f o

rticle history:eceived 6 March 2012eceived in revised form 16 March 2012ccepted 23 March 2012

eywords:leepalivary cortisolorking hours

a b s t r a c t

The buoyancy of humans in exploring extreme space environments has been established during missionsto the moon. Long duration missions like mission to Mars however, requires humans to adapt to systemicand complex environments beyond the human body’s capacity. Astronauts will encounter both physi-ological and psychological extremes during this trip. Very few studies are conducted on effect of longduration work and sleepiness on cognitive performance. So, this study was planned to find out effects ofleadership responsibility, sleepiness and long duration working hours on cognitive performance. The 30members (leadership: normal; 10:20) were selected from MDRS crews (Mars Desert Research Station,USA). Neurobehavioral test performance, self-ratings of fatigue and sleepiness, and salivary cortisol levels

Author's Personal Copy

eadershipeuro-behavioral

were evaluated during first day, mid and end day of mission. The leadership group did not show any signsof reduced test performance, even in elevated fatigue and sleepiness. The leadership group had fasterreaction times on end of mission as compared to first and after 7 day of mission. Salivary cortisol levelswere significantly higher in leadership group as compared to normal group. The results suggest that longduration work and sleepiness does not affect the cognitive performance of crew member. Further studyis required while taking into account all factors and large sample size to prove this fact.

© 2012 Elsevier Ireland Ltd. All rights reserved.

. Introduction

From the beginning of the space age, physicians, human fac-ors engineers, medical experts and psychologists expressed theironcerns about astronaut’s abilities to meet the physical, phys-ological, psychological requirements including neurobehavioralnd interpersonal demands of working in space [13,17,4]. Neu-obehavioral and physical deterioration is experienced due tonsufficient sleep and long working hours in astronauts duringong-duration manned space flights [10]. The performance and

orking ability of astronauts during long duration space flightepends heavily on achieving recovery through adequate sleep.leep loss and long working hours can affect the fundamentallements of human performance capability including vigilance,

ognitive speed and accuracy, working memory, reaction time,nd physiological alertness [10,2]. In some conditions, astro-auts have to work long time under stressed conditions in space

∗ Corresponding author at: Faculty of Earth & Life Sciences, Vrije Universiteitmsterdam & ILEWG, Amsterdam, The Netherlands. Tel.: +45 71579912.

E-mail addresses: drbalwantraissct@rediffmail.com,aibalwant29@gmail.com (B. Rai).

1 Resident: 112 1 tv, Cophengen 2200, Denmark.

304-3940/$ – see front matter © 2012 Elsevier Ireland Ltd. All rights reserved.ttp://dx.doi.org/10.1016/j.neulet.2012.03.067

environment. It has been reported that working more than 48–56 ha week is considered potentially harmful [14,15]. Working morethan 70 h a week accompanied with physical and mental stressdemanding job assignment is supposed to result in fatigue, whichfurther on effects health of astronaut and can result in failure ofspace exploration mission. To investigate the possible effects ofthis leadership responsibility and long duration working hours oncognitive performance and sleepiness using questionnaires, sali-vary cortisol levels, heart rate variability, muscular fatigue, sleepmonitoring, and neuro-behavioral tests, this study was planned.Extreme environments allow us to examine various aspects ofthe psycho-physiological relationship that is essential to fullyunderstand the concept of adaptation of humans to the stressfulconditions and long duration of working hours to comply withplanned experiments in these environments [8]. When crew teamsor individuals operate in extreme environments, their responsesare more purely a product of either situational drivers or inter-nal personal characteristics. The MDRS, Utah (USA) provides aunique opportunity to examine the interaction of salient indi-vidual factors such as gender and personality factors on social

relationships and group identity. The Mars Desert Research Sta-tion (MDRS) is an analog to a Mars surface habitat, constructed formission simulations according to Mars Reference Mission guide-lines [8], and located in a US southwest desert region relevant

178 B. Rai et al. / Neuroscience Letters 516 (2012) 177– 181

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week (p < 0.005). KSS score were significantly lower in leadershipteam [2.45 (SD 1.34)] as compared to normal team [5.23 (SD 1.89)](p < 0.05). Fatigue index score was significantly lower in leader-ship team as compared to normal team (p < 0.01, Table 2).There

Author's Personal Copy

Fig. 1. HAB (Mars Desert

o Mars analog geology, human factors and biology research.DRS includes an upper deck with six private staterooms having

ersonal storage and desks, a galley area, workstations, and meet-ng/eating area, plus a lower deck with a laboratory, toilet, shower,nd extra-vehicular activity (EVA) preparation rooms.Materialsnd methodsThe 30 members were selected from five crews.mong them, 10 crew members (Commander:Executive officer;:5) and 20 crew members (Chief scientist:Geologist:Crew engi-eer:Journalist:Health and safety officer; 6:5:1:4:5) were divided

nto leadership and normal team, respectively. The ages for theeadership aged 20–26 (23.6 (2.4)) while normal crew rangedrom 21 to 25 (23.5 (2.5) years). All of the crew members gaveheir written informed consent to participate. Crew structure andesponsibilities of different crew members has been described inable 1. Confined and isolated environment, international crewembers from different cultures, challenges to meet physical

emands (working in suits, science experiments, extravehicularctivities Figs. 1–5) as well as unavoidable Hab environmentalharacteristics (noise, isolation, confinement, low habitable volumeer person, and limited opportunities for variety and change) wasaced by all crew members. The both groups were tested on days 1first day of mission), 7 (mid-of mission), and 14 days (end of mis-ion). Karolinska Sleepiness Scale 5-point scale ((i) very alert, (ii)lert, (iii) neither alert nor sleepy, (iv) sleepy, no difficulty remain-ng awake, and (v) extremely sleepy, fighting sleep) was used forleep analysis [1]. Physiological and mental fatigue symptom rat-ngs were analyzed by 11 items [3]. The neuro-behavioral tests

ere analyzed using WAIS-R Digit Symbol substitution test; APTwo-choice visual reaction time and APT k test [3,16,11,9]. Maxi-

um heart rate was calculated [5]. Saliva was collected using thealiva Collection System (Greiner Bio-One GmbH, Kremsmunster,ustria), according to the manufacturer’s instructions. Smoking,ating and drinking were not permitted 30 min prior to collec-ion. Saliva samples were collected in morning between 0800nd 0820 on 1 (first day of mission), 7 (mid-of mission), and4 days (end of mission) and immediately stored at −4 ◦C. The

nalysis of salivary cortisol was performed using the RIA tech-ique [7]. Data were analyzed using SPSS (SPSS Inc.; Chicago, IL,SA).

arch Station, Utah, USA).

3. Results

Mean working hours of leadership group [80 (13)] was signif-icantly higher as compared to normal group [60 (11)] hours per

Fig. 2. Soil sampling.

B. Rai et al. / Neuroscience Letters 516 (2012) 177– 181 179

Table 1Brief structure of crew.

Simulating habitat on surface ofMars

Number of crew members and country Six, international (different part ofworld)

Crew structure 1. Commander (command andchief leader); 2. Health and safetyofficer; (oral and medicalphysician: take care of health ofcrew members); 3. Rover engineer(engineer specialized in roverdriving and maintaining); or crewjournalist (writing a story on crewactivity); 4. Crew geologist (takingsoil and rock samples); crewbiologist (specialized inextremophiles and microbiologicalstudy) or Chief scientist(specialized in basic science); 5.Executive officer (deputycommander and deputy leader ofcrew); 6. Hab Engineer (whoresponsible for taking care ofengineering works which requiredto make HAB work)

Duration Two weeksTypes of accommodations Staterooms with work areasMaintenance Power, electric, human waste,

waterTasking, scheduling and control All planning by crew members

under the supervision ofcommander; mission supportslogistics assistance; individualtasks; chores and sleeping timeopen to individuals

Communications Daily commander check in report;commander report; chef report;science report; engineering report;journalist report. Also, Posted withphotos on public web site

Mission timeline General planning in 2 weekspreceding; crew did not meetprior; crew member replaced infinal 2 weeks

Crew safety Focus on fire and medicalemergencies; flight surgeon on call

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Habitat construction Prefab panels assembled on site,ready for crew occupation

as typically no group difference for performance developmentetween days 1, 7 and end day of mission. Only one interac-ion effect between workday and group, involving the APT k testeaction time variable, was detected (Table 2). This interactionas due to the slower reaction times observed in the normal

eam group on day 1, which subsequently became faster andomparable with those observed in the leadership group on day

and 14 day (Tables 2 and 3). Heart rate and pulse rate wasot significantly higher on the end day in leadership group asompared to normal group. Salivary cortisol levels were signifi-antly higher in leadership group as compared to normal groupTable 4).

. Discussion

The working hours of leadership group were significantly highers compared to normal group. It might be due to more respon-ibility and more workload. This study reported that increasingymptoms of fatigue and sleepiness did not affect the performance,

.e. neuro-behavior in leadership group as compared to normalroup. The leadership group had the fastest reaction times on 14thay (end of mission) as compared to first and mid of mission. Itight be due to more learning effects as supported by WAIS-R Digit Ta

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180 B. Rai et al. / Neuroscience Letters 516 (2012) 177– 181

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able 3ifferent variable of fatigue, sleep and neurobehavioral in leadership group (univariate o

Leadership team

First day ofmissionMean (SD)

Mid-of missionMean (SD)

Karolinska Sleepiness Scale 2.34 (1.28) 2.11 (1.35)

Fatigue symptom index 1.67 (1.23) 1.69 (1.02)

WAIS-R Digit Symbol 52.9 (23.3) 51.3 (24.5)

APT RT-2, level 345 (113) 321 (156)

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APT RT inhibition variation 85 (24) 82 (21)

APT RT inhibition, failed variation ratio (%) 7.6 (2.4) 7.7 (3.4)

APT k test, RT level for correct responses 1456 (534) 1465 (675)

APT k test, error responses (%) e 3.3 (1.2) 3.0 (1.3)

AIS, Wechsler Adult Intelligence Scale; APT, Automated Psychological Test; RT, reactiona Post hoc paired samples t-test, p < 0.05, workday 1 versus workday 14.b Post hoc paired samples t-test, p < 0.05, workday 7 versus workday 14.

mpling.

Symbol test [12]. Salivary cortisol levels were significantly higher inleadership group as compared to normal group. It might be due tomore responsibility, long working hours, not enough time to sleep,more fatigue and more workload as supported by previous study[6]. Interestingly, even higher level of salivary cortisol levels didnot affect the reaction time in leadership group. It might be due tohigh motivation effect in leadership group as compared to normalgroup. It is also possible that these crew members, in order to keepthe current work schedule and the benefits there of, have had ansilent ambition to perform well the last workday as supported byresults, i.e. no difference in mean reaction time was observed for theAPT RT-2 test. In the APT k test, it involved a noticeably more com-plex visual search component, the mean reaction time decreasedby 112 ms. So, probably more complex tasks leave only one choicefor motivation to become an issue. To the best of our knowledge,there is no study of this nature reported in the literature, so it isvery difficult to compare this study results with any study.

At this point, some methodological issues need to be addressed.

The present plan has more than sufficient power to detect differ-ence between the means of the size of one standard deviation,both regarding main effects and interactions. This study has lots

ne-way repeated-measures analyses).

One-way repeated-measuresanalysis

End of missionMean (SD)

Main effect workday Polynomial contrast(linear effect)

2.02 (1.89) F = 0.789, p = 0.523 F = 1.34, p = 0.2341.67 (1.56) F = 11.34, p < 0.005 (partial

�2 = 0.24) (partial �2 = 0.27)F = 41.34, p < 0.005

59.8 (23.8)a,b F = 14.67, p < 0.005 (partial�2 = 0.27)

F = 39.45, p < 0.005(partial �2 = 0.47)

317 (134) F = 2.56, p = 0.092 F = 2.31, p = 0.07850 (26)a,b F = 4.85, p = 0.01 (partial

�2 = 0.13)F = 11.67, p = 0.002(partial �2 = 0.22)

300 (246)a,b F = 2.67, p = 0.094 F = 4.34, p = 0.045(partial �2 = 0.28)

80 (27) F = 2.67, p = 0.096 F = 4.68, p = 0.048(partial �2 = 0.15)

7.5 (3.1) F = 2.45, p = 0.124 F = 2.34, p = 0.1041312 (653)a,b F = 14.46, p < 0.005 (partial

�2 = 0.28)F = 23.46, p < 0.005(partial �2 = 0.43)

2.8 (1.9) F = 0.67, p = 0.658 F = 0.78, p = 0.678

time.

B. Rai et al. / Neuroscience Letters 516 (2012) 177– 181 181

Table 4Salivary cortisol levels in leadership and normal group.

Variable Leadership group Normal group

First day of missionMean (SD)

Mid-of missionMean (SD)

End of missionMean (SD

First day of mission Mid-of mission End of mission

Salivary cortisol levels (ng/l) 14.90 (3.32) 32.62 (6.45) 31.34 (7.

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f limitations such as small sample size, not taking to account fac-ors such as noise level, international and cultural differences, dietestrictions, no objective method used for sleep analysis, so, furthertudy is required on large sample size and taking into account allossible factors to prove the fact of this study. The results showedhat implementing a demanding long hours of work schedule suchs 80 h per week do not affect the cognitive performance of crewember.

cknowledgement

We would like to express gratitude towards the Mars Society,

LEWG, ESA/ESTEC, l’Ecole de l’Air, Prof. Bernard Foing, Dr. Guy Pig-olet from the SALM institute, Mr. Akos Kerezturi, Dr. Tamarackzarnik, Dr Carol Stoker (NASA Ames), the Mission Support, Mr. Donusko and all other related people for their daily assistance and our

[

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) Mean (SD) Mean (SD) Mean (SD)

45) 11.56 (5.23) 13.24 (6.12) 14.21 (3.45)

remote supporters from America, Europe, Canada and JBR researchgroup India. We are thankful to Mag. Michaela Neuhofer (Prod-uct Manager Saliva Systems, Clinical Research Laboratory/GreinerBio-One GmbH, Gewerbepark 2, A-4261 Rainbach im Mühlkreis)and Lisbet Forland (Greiner Bio-One, Hettich Lab instrument ApS,Denmark) for providing us saliva collection devices and technicalsupport.

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