Could wearing an eye mask make you smarter, by boosting deep sleep?

Ambient light at night has been shown to disrupt the depth of sleep - so could wearing an eye mask improve sleep quality, and our ability to learn?

This was the question asked by researchers at Cardiff University... Viviana Greco and colleagues recruited 18-35 year olds for two studies to investigate the impact of wearing an eye mask overnight.

In the first study, 89 volunteers were randomised to either wear a standard eye mask which blocked out light, or an eye mask with holes over the eyes (as a control comparison) for 7 nights. On the 6th and 7th days, they were invited into the lab to complete cognitive tests of sleepiness, reaction time and learning. All the participants repeated the tests under both conditions - with and without the standard eye mask.

• What were the results? Wearing an eye mask was associated with a significant improvement in learning word-pairs and significantly improved reaction time. However there was no difference in overall sleep time, or self-reported sleepiness.

In the second study, 35 volunteers repeated the protocol but this time they wore a Dreem headband to measure sleep staging.

• What were the results? Although there was no statistically significant difference detected in slow wave sleep between the two conditions, there was a correlation between the amount of slow wave sleep and the ability to learn word-pairs.

The researchers concluded that blocking ambient light using an eye mask was associated with increased alertness and ability to learn new information the next day. These memory benefits were attributed to increased slow wave sleep.

This was a relatively small, short term study looking at just one week of wearing an eye mask.. but suggests that "wearing an eye mask during sleep is an effective, economical, and noninvasive behavior that could benefit cognitive function and lead to measurable impacts on everyday life".