We hear it all the time: you should sleep at least seven hours per night, preferably eight or nine. However, what is often missing from the public service announcement is that you’d better make sure those are quality hours of shuteye. But if you live in a busy city that never rests, distractions like honking vehicles or bright lights may mess up with your sleep, prompting you to wake up without even realizing it.

Many turn to the humble eye mask to sleep more soundly and minimize disruption. As it turns out, they’re on to something.

According to a new study, people who wore an eye mask during sleep experienced enhanced memory encoding and alertness the subsequent day.

Eye masks may enhance deep sleep

As our understanding of sleep deepens, we’re learning that sleep isn’t just a period of rest; it’s a complex dance of brain activity and bodily restoration. Studies have long highlighted the significance of sound sleep for our mental and physical well-being. Yet often disruptive sources of light can have profound effects on our daily lives. Ambient light, be it from streetlights or electronic devices, can seep into our retinas, throwing a wrench into our natural sleep-wake cycle.

In a bid to combat the intrusion of light into sleep, a team of researchers led by Viviana Greco, a Ph.D. candidate at Cardiff University’s Brain Research Imaging Centre, embarked on a study to explore whether eye masks actually work in enhancing sleep quality.

To this aim, the researchers conducted two experiments. The first experiment involved 89 participants between 18 and 35 years old. Over the span of two weeks, the participants wore an eye mask during sleep for one week and experienced a control condition with no mask during the other.

What they found was intriguing — those who slept with the eye mask exhibited superior performance on a word-pair association task and demonstrated heightened alertness as measured by a psychomotor vigilance test. These results strongly suggested that the eye mask positively influenced both alertness and episodic memory encoding.

For the second experiment, the scientists delved deeper into the impact of eye masks. They recruited 33 participants of similar ages and introduced a twist in the first experiment. Participants spent two nights with a regular eye mask and two nights with a cutout mask that covered their faces but left their eye region uncovered. While participants’ self-reported sleep quality remained consistent across conditions, their learning performance on the paired associative learning task showed marked improvement after wearing the eye mask.

The data gathered by the researchers suggests that the memory benefits derived from wearing the eye mask were closely tied to the amount of slow-wave sleep experienced by participants. Slow wave sleep, also known as deep sleep, is a phase during which the brain is thought to consolidate memories and restore its ability to encode new information. The researchers speculated that the eye mask might facilitate increased slow wave activity, leading to the observed memory enhancements.

Our daily lives are replete with tasks that demand quick thinking and swift responses, such as driving or learning new information. Greco emphasizes that wearing an eye mask can be an affordable and accessible means of enhancing cognitive performance. By harnessing the power of improved memory encoding and alertness, we can potentially navigate these challenges with greater precision and clarity.

In our quest for quality sleep, the solution may lie just a comfortable sleep mask away.

The findings appeared in the journal Sleep.