What happens when someone who is extremely sensitive to light puts zDen to the test for more than a year?
The Guardian writer Tracy Allison recently shared her experience with the zDen Personal Sleep Sanctuary after using it nearly every night since May 2025. She had already tried blackout curtains and an eye mask, but even small amounts of light could still interfere with her sleep.
With zDen, Tracy found a way to create darkness where she actually sleeps. She even packed it for a three-week road trip through Ireland, where summer daylight can last well into the evening.
Her experience highlights something that is easy to overlook:
Most bedrooms are not as dark as people think.
And sometimes the answer is not trying to make the entire room dark. It is creating darkness where you actually sleep.
Read Tracy Allison’s full independent review in The Guardian
Your Sleep Environment May Not Follow Your Sleep Schedule
Your body may be ready for sleep even when the world around you is not.
Night-shift workers may need to sleep while sunlight is streaming through the windows. College roommates may keep completely different schedules. One partner may want to watch TV or read while the other sleeps. Parents, caregivers, travelers, and people living in shared spaces may have little control over the entire room.
Even with blackout curtains, light can still come from sources inside the room.
That is why it can be helpful to look beyond the windows and pay attention to the space where you actually sleep.
Look Beyond the Blackout Curtains
Blackout curtains can be an important part of creating a dark bedroom, but they cannot address every source of light.
Take a look around your sleep space at the time you normally sleep. Can you see:
- Light coming around the edges of curtains or shades?
- Charging lights or electronics?
- Light coming through or under the door?
- A television, phone, or other screen being used by someone else?
- Nightlights or hallway lights?
- Early morning sunlight before you are ready to wake?
- Daylight because your work or sleep schedule does not follow traditional nighttime hours?
Some light sources may be easy to change. Others may be part of a shared room, household, dorm, hotel, or work schedule that you simply cannot control.
Create Darkness Where You Sleep
zDen was created around a simple idea: instead of requiring the entire room to adapt to one person's sleep schedule, create a personal, private dark sleep zone where sleep actually happens.
The zDen Personal Sleep Sanctuary blocks over 99% of sleep-disrupting light. Its patented upper-body-only design creates a spacious dark sleep space for the upper body while leaving the rest of the body outside.
That can be especially useful when the environment around you needs to remain bright or active, whether you are sleeping during the day, sharing a bedroom, living in a dorm, staying in a hotel, or simply dealing with light that blackout curtains cannot eliminate.
And because zDen is lightweight and portable, your personal sleep environment can travel with you.
That portability became especially meaningful in Tracy's experience. Rather than wondering whether each new hotel or accommodation would be dark enough, she could bring a familiar dark sleep space with her.
Darkness Is Important, But It Is Only One Part of Sleep Hygiene
Your sleep environment matters, but better sleep hygiene is about more than darkness.
Your sleep and wake schedule, waking-hour habits, caffeine timing, physical activity, wind-down routine, light and screen exposure, mental unwinding, and the comfort of your sleep space can all affect how well your habits support sleep.
Sometimes the challenge is simply knowing where to begin.
Not Sure Where to Start?
The free zDen Sleep Hygiene Check-In can help you take a closer look at your current habits, routines, and sleep environment.
After completing the Check-In, you receive a personalized educational summary that helps you notice what may already be supporting your sleep and where there may be opportunities for improvement.
The Check-In looks at several areas of sleep hygiene, including:
- Your sleep-wake routine
- Your waking-hours foundation
- Your wind-down routine
- Your mental unwinding habits
- Your sleep-space sanctuary
You do not need to change everything at once.
The goal is to notice patterns, identify one area that stands out, and choose one realistic change you can try for the next seven days.
Take the Free Sleep Hygiene Check-In
Better Sleep Can Start With One Small Change
Creating better conditions for sleep does not have to mean completely redesigning your bedroom or changing your entire routine overnight.
Look at your habits. Look at your environment. Notice what happens before you sleep and what may be disrupting your sleep once you get there.
Then choose one thing that feels realistic to change.
Maybe it is covering a charging light. Lowering the lights before bedtime. Adjusting your caffeine timing. Creating a more consistent wind-down routine. Or finding a better way to create darkness when you cannot control the entire room.
Sometimes better sleep starts by noticing something you had stopped noticing.
Want a place to start?
Take the Free Sleep Hygiene Check-In
Want to read what happened when Tracy Allison used zDen for more than a year?
Read the full independent review in The Guardian
Here’s to better sleep, anytime, anywhere.