Can the use of a sleep mask improve alertness and cognitive abilities? Eric Zhou, PhD, Assistant Professor at Harvard Medical School, addresses this question by citing a study published in the journal Sleep in 2023 by researchers at Cardiff University in the UK.
As part of the study, approximately 90 adults aged 18 to 35 underwent a sleep phase involving a mask that completely blocked out light, as well as a corresponding procedure with a mask that allowed light to pass through a small hole in the fabric. The participants were required to keep sleep diaries throughout.
Each phase lasted one week. On days 6 and 7 of each phase, with or without minimal light, the participants underwent three cognitive tests:
- Paired-associates learning test: This test assesses an individual’s ability to learn new associations. In this case, it involved learning paired-word associations. Participants who had slept with the light-blocking mask in previous nights performed better.
- Psychomotor vigilance test: In this test as well, the results favoured the group with complete darkness.
- Motor skill learning test: Participants were required to press a sequence of five digits in the correct order. This test showed no differences between the two groups.
“No research is perfect, so let’s approach the findings with some reservations,” comments Professor Zhou, explaining:
- According to the data from the sleep diaries, there was no difference in sleep duration or perceived sleep quality, regardless of whether or not a sleep mask was used.
- In a second experiment involving approximately 30 participants, the researchers monitored sleep using a recording device placed on the participants’ heads for more objective assessments, and no changes were found in sleep stages.
Is a sleep mask a solution?
If you need or want to sharpen your cognitive abilities, instead of purchasing a sleep mask, consider adopting the chronobiologist’s rule of “days with light, nights with darkness”:
- During the day, maximise your exposure to natural light. Go out for breakfast, take a short walk during your work break.
- In the evening, limit your use of electronic devices like your mobile phone, and opt for night mode. Make sure to turn off all unnecessary lights. Finally, strive for a dark bedroom.
(information from ygeiamou.gr)
