Slow release caffeine and prolonged (64-h) continuous wakefulness: effects on vigilance and cognitive performance

Area of Science:

• Neuroscience
• Human Physiology
• Pharmacology

Background:

• Shift work and long work hours often lead to sleep deprivation (SD), impairing vigilance and cognitive performance.
• Maintaining optimal performance under prolonged wakefulness is crucial in many operational settings.

Purpose of the Study:

• To investigate the effects of slow-release caffeine (SRC) on vigilance and cognitive functions during extended sleep deprivation.
• To determine if SRC can mitigate the negative impacts of 64 hours of continuous wakefulness.

Main Methods:

• A double-blind, randomized, placebo-controlled, crossover study involving 16 healthy males.
• Participants received either 600 mg of SRC daily (300 mg twice daily) or a placebo (PBO) during a 64-hour sleep deprivation period.
• Vigilance was assessed using electroencephalogram (EEG), multiple sleep latency tests (MSLT), and actigraphy. Cognitive functions, attention, and alertness were measured using standardized computer tests and visual analogue scales (VAS).

Main Results:

• SRC significantly improved vigilance throughout the 64-hour sleep deprivation period compared to placebo, as indicated by MSLT results (P<0.0001).
• Certain cognitive functions were enhanced by SRC for up to 33 hours of SD, while others showed improvement throughout the entire period.
• Alertness, measured by the Stroop's test, was significantly better from the 13th hour of SD onwards in the SRC group (P=0.048).

Conclusions:

• Twice-daily administration of 300 mg SRC effectively counteracts the detrimental effects of 64 hours of sleep deprivation on vigilance and cognitive performance.
• SRC represents a viable countermeasure for maintaining cognitive function and alertness in situations of prolonged wakefulness.