Mindfold Sleep Mask — Total Darkness for Better Sleep

Not a regular sleep mask — the Mindfold blocks 100% of light while letting you open your eyes.

The Mindfold is a sleep mask with a foam cavity that creates total darkness while letting you open your eyes freely. Willem tested it with Whoop sleep data — the results were measurable.

Most sleep masks press against your eyelids and let light leak in from the sides. The Mindfold is different: a rigid foam shell creates a dark cavity in front of your eyes. You can open your eyes freely — you just see nothing.

The effect on sleep is measurable. Using his Whoop Strap, Willem tracked sleep quality before and after adopting the mask. Deep sleep percentages improved, and time-to-fall-asleep decreased — especially in environments with ambient light (hotels, summer evenings, early mornings).

The mask also works for napping: total darkness triggers melatonin production faster than a dark room, because even small amounts of light through closed eyelids suppress melatonin.

From Willem's writing on wearable sensors and health data.