title: Decreased salivary alpha-amylase levels are associated with performance deficits during sleep loss.
abstract: During sleep deprivation, neurobehavioral functions requiring sustained levels of attention and alertness are significantly impaired. Discrepancies between subjective measures of sleepiness and objective performance during sustained operations have led to interest in physiological monitoring of operator performance. Alertness, vigilance, and arousal are modulated by the wake-promoting actions of the central noradrenergic system. Salivary alpha-amylase (sAA) has been proposed as a sensitive peripheral measure of noradrenergic activity, but limited research has investigated the relationship between sAA and performance. In a laboratory-controlled environment, we investigated the relationship between sAA levels, subjective sleepiness, and performance during two days (50h) of total sleep deprivation. Beginning at 09:00, twelve healthy participants (5 females) aged 22.5±2.5years (mean±SD) provided saliva samples, recorded ratings of subjective sleepiness, completed a brief 3-min psychomotor vigilance task (PVT-B) and performed a 40-min simulated driving task, at regular 3h intervals during wakefulness. Ratings of subjective sleepiness exhibited a constant linear increase (p<0.001) during sleep deprivation. In contrast, sAA levels showed a marked diurnal profile, with levels increasing during the day (p<0.001) and steadily declining in the evening and early-morning (p<0.001). PVT-B (mean reaction time and mean slowest 10% reaction time) and simulated driving performance (speed deviation and lane deviation) also exhibited diurnal profiles across the two days of sleep deprivation. Performance peaked in the afternoon (p<0.001) and then steadily worsened as wakefulness continued into the evening and early-morning (p<0.001). Further analysis revealed that higher sAA levels in the hour preceding each performance assessment were associated with better PVT-B and driving performance (p<0.001). These findings suggest that sAA measures may be suitable indicators of performance deficits during sustained wakefulness and highlight the potential for sAA to be considered for physiological monitoring of performance. In operational environments sAA levels, as part of a panel of physiological measures, may be useful for assessing fitness-for-duty prior to safety being compromised or when performance deficits are unknown.
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia. Electronic address: maja.pajcin@mymail.unisa.edu.au.
authors.forename: Maja
authors.initials: M
authors.lastname: Pajcin
authors.affiliation: Centre for Sleep Research, University of South Australia, Adelaide, Australia.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Banks
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia.
authors.forename: Jason M
authors.initials: JM
authors.lastname: White
authors.affiliation: Centre for Sleep Research, University of South Australia, Adelaide, Australia.
authors.forename: Jill
authors.initials: J
authors.lastname: Dorrian
authors.affiliation: Centre for Sleep Research, University of South Australia, Adelaide, Australia.
authors.forename: Gemma M
authors.initials: GM
authors.lastname: Paech
authors.affiliation: Centre for Sleep Research, University of South Australia, Adelaide, Australia.
authors.forename: Crystal
authors.initials: C
authors.lastname: Grant
authors.affiliation: Land Division, Defence Science and Technology Group, Department of Defence, Edinburgh, South Australia, Australia.
authors.forename: Kayla
authors.initials: K
authors.lastname: Johnson
authors.affiliation: Land Division, Defence Science and Technology Group, Department of Defence, Edinburgh, South Australia, Australia.
authors.forename: Katie
authors.initials: K
authors.lastname: Tooley
authors.affiliation: Land Division, Defence Science and Technology Group, Department of Defence, Edinburgh, South Australia, Australia.
authors.forename: Justin
authors.initials: J
authors.lastname: Fidock
authors.affiliation: Behavioral Biology Branch, Walter Reed Army Institute for Research, Silver Springs, MD, United States.
authors.forename: Gary H
authors.initials: GH
authors.lastname: Kamimori
authors.affiliation: School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia.
authors.forename: Chris B
authors.initials: CB
authors.lastname: Della Vedova
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D001334:Automobile Driving; D005260:Female; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D055291:Salivary alpha-Amylases / Q000032:analysis*; D012892:Sleep Deprivation / Q000503:physiopathology*; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
chemical_list: D055291:Salivary alpha-Amylases
keywords: Amylase; Biomarker; Performance; Saliva; Sleep deprivation; Sleepiness