PhotoMost everyone knows how important sleep is to infants and children, but there are still many adults out there who only get a few hours of sleep per night. While these same people might reach for coffee in the morning to counteract a poor night’s sleep, a new study shows that caffeine can only help so much.

In a double-blind, placebo-controlled study, researchers found that caffeine was only able to help improve alertness and performance in adults for two consecutive days before lack of sleep took over.

Temporary benefits

The researchers utilized 48 individuals who were restricted to five hours of sleep per 24-hour period over the course of five days. Participants were split into two groups for the study – one group received 200 mg of caffeine twice daily while the other received a placebo.

Over the five-day period, all participants also took part in a range of tests to measure their alertness and overall cognitive performance. The researchers found that while the group receiving caffeine did better on these tests over the first two days of the trial period, the lack of sleep eventually caught up with them and their scores suffered over the final three days.

“We were particularly surprised that the performance advantage conferred by the two daily 200 mg doses of caffeine was lost after three nights of sleep restriction,” said Dr. Tracy Jill Doty, lead author of the study.

Prioritizing sleep

The results indicate that caffeine may not suffice if a person is repeatedly not getting enough sleep at night. For consumers who need to stay alert during their waking hours, which pretty much includes everyone for one reason or another, this could mean prioritizing sleep in the future.

“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 or restricted sleep,” said Doty.

The abstract for this study has been published in the journal Sleep, but the research team plans to present their full findings on June 14 at SLEEP 2016, an annual meeting of members of the Associated Professional Sleep Societies LLC (APSS).

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