Effects of strategic early-morning caffeine gum administration on association between salivary alpha-amylase and neurobehavioural performance during 50 h of sleep deprivation

• Published in: Accident analysis and prevention 2019-05, Vol.126, p.160-172
• Main Authors: Pajcin, Maja, White, Jason M, Banks, Siobhan, Dorrian, Jill, Paech, Gemma M, Grant, Crystal L, Johnson, Kayla, Tooley, Katie, Aidman, Eugene, Fidock, Justin, Kamimori, Gary H, Della Vedova, Chris B
• Format: Article
• Language: English
• Subjects: Adult; Alpha-amylase; Attention - drug effects; Biomarker; Caffeine; Caffeine - administration & dosage; Caffeine - pharmacology; Central Nervous System Stimulants - administration & dosage; Central Nervous System Stimulants - pharmacology; Double-Blind Method; Female; Humans; Male; Polysomnography; Psychomotor Performance - physiology; Reaction Time - drug effects; Saliva; Salivary alpha-Amylases - drug effects; Sleep deprivation; Sleep Deprivation - physiopathology; Wakefulness - drug effects; Young Adult
• ISSN: 0001-4575; 1879-2057
• DOI: 10.1016/j.aap.2018.01.026

•Caffeine affected diurnal profiles of sAA and performance on Day 1, but not Day 2.•Diurnal profiles of sAA and performance in caffeine on Day 2 were similar to placebo.•sAA was associated with vigilance during first 24 h of wakefulness.•sAA was consistently associated with response speed across 48 h of wakefulness.•Association between sAA and performance was weaker as compared with placebo. Self-assessment is the most common method for monitoring performance and safety in the workplace. However, discrepancies between subjective and objective measures have increased interest in physiological assessment of performance. In a double-blind placebo-controlled study, 23 healthy adults were randomly assigned to either a placebo (n = 11; 5 F, 6 M) or caffeine condition (n = 12; 4 F, 8 M) while undergoing 50 h (i.e. two days) of total sleep deprivation. In previous work, higher salivary alpha-amylase (sAA) levels were associated with improved psychomotor vigilance and simulated driving performance in the placebo condition. In this follow-up article, the effects of strategic caffeine administration on the previously reported diurnal profiles of sAA and performance, and the association between sAA and neurobehavioural performance were investigated. Participants were given a 10 h baseline sleep opportunity (monitored via standard polysomnography techniques) prior to undergoing sleep deprivation (total sleep time: placebo = 8.83 ± 0.48 h; caffeine = 9.01 ± 0.48 h). During sleep deprivation, caffeine gum (200 mg) was administered at 01:00 h, 03:00 h, 05:00 h, and 07:00 h to participants in the caffeine condition (n = 12). This strategic administration of caffeine gum (200 mg) has been shown to be effective at maintaining cognitive performance during extended wakefulness. Saliva samples were collected, and psychomotor vigilance and simulated driving performance assessed at three-hour intervals throughout wakefulness. Caffeine effects on diurnal variability were compared with previously reported findings in the placebo condition (n = 11). The impact of caffeine on the circadian profile of sAA coincided with changes in neurobehavioural performance. Higher sAA levels were associated with improved performance on the psychomotor vigilance test during the first 24 h of wakefulness in the caffeine condition. However, only the association between sAA and response speed (i.e. reciprocal-transform of mean reaction time) was consistent across both days of sleep deprivation. The ass