The effects of chewing versus caffeine on alertness, cognitive performance and cardiac autonomic activity during sleep deprivation

Nov 23, 2006Journal of sleep research

Chewing and caffeine effects on alertness, thinking skills, and heart activity during sleep loss

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Abstract

Chewing did not improve alertness or cognitive performance compared to placebo in a study involving 14 adults.

Participants performed cognitive tasks each hour during a night without sleep.
Caffeine (200 mg) improved speed and accuracy on cognitive tasks and increased alertness compared to chewing.
Heart rate and measures of cardiac autonomic activity did not differ significantly between chewing and placebo conditions.
Chewing was associated with a reduction in preejection period in the later part of the night compared to placebo.
Strong associations were found between cardiac parasympathetic activity and complex cognitive tasks, indicating different mediating processes for task difficulty.

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Chewing has been shown to alleviate feelings of sleepiness and improve cognitive performance during the day. This study investigated the effect of chewing on alertness and cognitive performance across one night without sleep as well as the possible mediating role of cardiac autonomic activity. Fourteen adults participated in a randomized, counterbalanced protocol employing a chewing, placebo and caffeine condition. Participants completed tasks assessing psychomotor vigilance, tracking, grammatical reasoning, alertness and sleepiness each hour across the night. All participants received either placebo or caffeine (200 mg), while the chewing condition also chewed on a tasteless and odorless substance for 15 min each hour. Heart rate (HR), root mean square of the successive differences in R-R intervals on the ECG (RMSSD), and preejection period (PEP) were simultaneously recorded. Alertness and cognitive performance amongst the chewing condition did not differ or were in fact worse when compared with placebo. Similarly, measures of HR and RMSSD remained the same between these two conditions; however, PEP was reduced in the later part of the night in the chewing condition compared with a relative increase for placebo. Caffeine led to improved speed and accuracy on cognitive tasks and increased alertness when compared with chewing. Relative increases in RMSSD and reductions in HR were demonstrated following caffeine; however, no change in PEP was seen. Strong associations between cardiac parasympathetic activity and complex cognitive tasks, as well as between subjective alertness and simpler cognitive tasks, suggest a differential process mediating complex versus simple cognitive performance during sleep deprivation.

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The effects of chewing versus caffeine on alertness, cognitive performance and cardiac autonomic activity during sleep deprivation

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