Caffeine not effective after 3 nights of sleep restriction

Researchers from the Walter Reed Army Institute of Research found that alertness and performance sustainability deteriorated after 3 days despite caffeine use, according to findings presented at the SLEEP 2016 annual meeting.

They conducted a double-blind, placebo-controlled study of 48 healthy participants to analyze the efficacy of caffeine use during sleep restriction.

The participants followed the subsequent protocol: 5 nights with 10 hours of time in bed, baseline testing, 5 nights with 5 hours of time in bed with 200 mg caffeine or placebo twice daily and then 3 days with 8 hours of time in bed. They underwent a variety of testing, including a modified Maintenance of Wakefulness Test (mMWT), Stanford Sleepiness Scale (SSS), Profile of Mood States (POMS) and a 10-minute Psychomotor Vigilant Task (PVT).

Results showed that caffeine was associated with improved PVT during the first 2 days of sleep restriction, but not during the last 3 days. This was also true of sleep latencies and improved happiness ratings.

The researchers also reported that participants who received caffeine during the study were more annoyed than participants who received placebo in the latter days of the sleep restriction period.

"The efficacy of caffeine for maintaining alertness and performance wanes across 3+ days of sleep restriction," the researchers concluded. "The extent of this decline as a function of the (possibly interactive) effects of mounting sleep debt and high cognitive load remains to be determined."

"We were particularly surprised that the performance advantage conferred by two daily 200 mg doses of caffeine was lost after 3 nights of sleep restriction," Tracy Jill Doty, PhD, lead study author, said in a press release. "These results are important, because caffeine is a stimulant widely used to counteract performance decline following periods of restricted sleep. The data from this study suggests that the same effective daily dose of caffeine is not sufficient to prevent performance decline over multiple days of restricted sleep." – by Chelsea Frajerman Pardes

Reference:

So CJ, et al. Caffeine efficacy across a simulated 5-day work week with sleep restriction. Presented at: SLEEP Annual Meeting 2016; June 11-15; Denver.

Disclosures: The study was supported by the Department of Defense Military Operational Medicine Research Program (MOMRP).