Multiple caffeine doses maintain vigilance, attention, complex motor sequence expression, and manual dexterity during 77 hours of total sleep deprivation

Abstract

Sleep deprivation (SD) and fatigue have detrimental effects on performance in operational settings. Few studies have investigated the cumulative effects of SD and fatigue on performance under heavy workload demands. Therefore, we investigated the efficacy of multiple repeated doses of caffeine as a countermeasure to SD and fatigue during 77 h total SD (TSD) during the early morning hours. Twenty-three males and females, 18 - 35 years of age, who identified as moderate caffeine consumers completed the Psychomotor Vigilance Task (PVT) 141 times during the experimental test period. Caffeine was administered in a multi-dose paradigm over three nights without sleep. Participants received either caffeine (200 mg) or placebo at the beginning of each 2-h test block from 0100 - 0900 (800 mg total per night). While PVT speed declined for both groups across all 3 nights, the caffeine group consistently out-performed the placebo group. Caffeine maintained attentiveness (1-5 s lapses) on night 1, but this advantage was lost on nights 2 and 3. Caffeine outperformed placebo for responsive lapses (5-9 s lapses) across all three nights, but caffeine performance was still notably worse than at baseline. Prolonged non-responsive lapses (beyond 10 s) were only reduced by caffeine on night 2. Caffeine was more effective than placebo across all nights at sustaining completion speed of a complex motor sequence task and a manual coordination task. Essentially, caffeine is an effective countermeasure for SD, as it mitigates declines in speed and failures to respond, and sustains motor planning and coordination. However, caffeine does not restore normal functioning during SD and cannot be considered as a replacement for sleep.

Keywords: Attention; Boredom/monotony; Caffeine; Grooved pegboard; Multi dose paradigm; PVT; Total sleep deprivation; Tower of Hanoi; Vigilance.

Conflict of interest statement

The authors have no conflicts of interest to declare.

© 2020 The Authors. Published by Elsevier Inc.

Figures

Fig. 1

Study procedure and timeline. Day describes the number of days participants remained in the lab. Night describes nights of sleep deprivation and experimental testing. Psychomotor Vigilance Task; TOH – Tower of Hanoi; GP – Grooved Pegboard. Caffeine gum administrations in bold. aTime block details: Provides a detailed description of each time block during the experimental test days. PVTb – PVT, SSS, and SEQ were administered.

Fig. 2

Tasks used to assess the effects of sleep deprivation. A) Palm-PVT: a 5-min version of the psychomotor vigilance test (PVT) administered on a hand-held personal assistant device. Participants were required to press one of the response keys at the bottom of the device as quickly as possible each time the “bullseye” target appeared. Response time was displayed in the center. B) Grooved Pegboard (BP): participants were required to place oddly shaped metal pegs in small keyholes as rapidly as possible. C) Tower of Hanoi (TOH): Participants were required to move a stack of colored rings from peg A to peg C as quickly as possible, while following the rules that only one ring could be moved at a time, and that a larger ring could never be placed on top of a smaller ring.

Fig. 3

Caffeine and placebo group performance for a) mean speed (error bars represent ± 1 SE) b) frequency counts of attentional lapses—AL c) frequency counts of responsive lapses—RL and d) frequency counts of non-responsive lapses—NRL on all 3 nights for all 4 blocks including baseline from Night 1.

Fig. 4

Mean completion time for the Tower of Hanoi (TOH) puzzle at each block.

Fig. 5

Mean completion time for the Grooved Pegboard (GP) task at each block.