Greco’s team found that measures of memory formation and alertness actually improved when participants wore the masks to sleep.

To explore the topic further, they designed a second experiment in which a smaller group of 35 adults wore a sleep mask for five nights and then a sleep mask with eye holes cut out for two nights. This was to serve as a control mask that gave the participants the sensation of sleeping with a mask on without blocking the light. They also wore EEG headbands to measure sleep stages during this follow-up study.

Again, those with the real mask performed better on cognitive tests after the study. After analyzing the EEG data, the researchers hypothesized that this may be due to an increase in slow-wave activity in the brain while wearing sleep masks, which block light from reaching the retina.

“Given the current climate of life hacking, sleep monitoring, and cognitive enhancers, our findings suggest that an eye mask is a simple, cost-effective, and non-invasive way to get more out of a night’s sleep,” the study authors conclude.

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