How dark should the bedroom be?

The Biology of Darkness: Why We Need to See Black

understand the ideal lighting conditions for a bedroom , we need to take a look inside the human brain, more precisely at the pineal gland. It is our internal light sensor.

The melatonin mechanism

As soon as it gets dark, the pineal gland begins producing melatonin. This hormone makes us tired and lowers body temperature and blood pressure.

• The problem: When light hits the retina – even through closed eyelids – this signals "daytime" to the brain. Melatonin production is reduced.
• The consequence: If the lighting in your bedroom is too bright, you'll fall asleep later and wake up more frequently during the night. In the long term, this is linked to an increased risk of diabetes, obesity, and depression. Therefore, dim lighting in the bedroom is essential for your health .

How dark is dark enough?

Scientists give a clear answer here: As dark as possible.

• The limit: Studies show that even a light intensity of 5 to 10 lux (roughly equivalent to a bright streetlamp at a distance) can disrupt sleep. Ideally, optimal lighting conditions in bedrooms are below 1 lux.
• The hand test: A simple method to check the lighting in your bedroom : If you're lying in bed and can't see your hand in front of your face, it's dark enough. If you can see the outline of your hand or furniture in the room, the lighting in your bedroom needs improvement.

External light sources: The enemy outside the window

In urban areas such as Zurich, Basel or Geneva, "light pollution" is a massive disruptive factor for healthy lighting conditions in bedrooms .

Street lighting and traffic

Light penetrating from the outside is often bluish and therefore particularly effective at keeping you awake.

• Curtains vs. blinds: Light curtains only filter light; they don't block it completely. To create perfect lighting conditions in a bedroom , exterior blinds (standard in Switzerland) are ideal.
• Blackout curtains: If you don't have roller shutters (e.g., in older buildings), blackout curtains are essential. They are specially coated and let 0% of light through. Make sure they are wide enough on the sides to prevent light gaps that could ruin the lighting in your bedroom .

The moon

Even a full moon can be bright enough in rural areas (up to 0.3 lux) to disturb sensitive sleepers. Here too, the rule applies: anyone who wants to control the light levels in their bedroom must be able to completely darken the room.

Internal light sources: The danger from within

We often sabotage the lighting conditions in bedrooms ourselves through electronic devices.

Standby lights

The red dot on the television, the green light of the router, or the display of the humidifier – these mini-LEDs add up.

• Visual noise: In complete darkness, these points act like spotlights. They attract the eye and disrupt the mental lighting conditions in the bedroom .
• Solution: Cover all status LEDs with special masking tape ("dimmer stickers") or remove the electronics completely. This is the only way to achieve uncompromising lighting conditions in the bedroom .

The alarm clock

The classic digital alarm clock with illuminated numbers is a relic that disrupts sleep. Every time you wake up at night and see the light, your brain is stimulated.

• Recommendation: Use alarm clocks whose display remains dark and only lights up when a button is pressed. This protects the dim lighting conditions in bedrooms .

Blue light and screens

A special case of bedroom lighting conditions is the light we expose ourselves to before going to sleep.

The blue light from smartphones and tablets has a wavelength that massively suppresses melatonin production – more so than any other light.

• The rule: Screens should not be used for at least 60 minutes before bedtime. Scrolling in bed directly alters the lighting conditions in the bedroom and disrupts one's sleep rhythm.

Waking up: When light is desired

Just as darkness is important for falling asleep, light is equally important for waking up. The lighting conditions in the bedroom must change dynamically in the morning.

Cortisol boost

Light in the morning signals the body to stop melatonin production and release cortisol (the wake-up hormone).

• Daylight alarm clock: In completely dark rooms (e.g., with blinds), this stimulus is missing. A daylight alarm clock (wake- up light) simulates sunrise. It gradually changes the light conditions in the bedroom from red to orange to light yellow, even before the alarm rings. This makes waking up gentler.
• Smart Home: Intelligent roller shutters that open slowly are the luxury option for automatically optimizing the lighting conditions in the bedroom in the morning.

Afraid of the dark?

Some people, especially children, feel uncomfortable in complete darkness. How can this be reconciled with healthy lighting conditions in the bedroom ?

• Red nightlight: If a light is needed, choose red or amber. Red light has the least impact on melatonin production . A dim, floor-level nightlight hardly changes the lighting conditions in the bedroom negatively, but provides psychological security.

Conclusion

The question "How dark should the bedroom be?" can be answered scientifically with a clear answer: So dark that you can no longer see your own hand in front of your face. The lighting conditions in the bedroom are a fundamental building block of your health. Every light source, be it a streetlamp, can contribute to this. Whether it's outside or the standby LED inside, it's a potential disruptive factor for your hormonal balance.

Invest in good blackout solutions. Critically check your bedroom at night for light leaks and eliminate electronic sources of interference. Those who consistently optimize bedroom lighting for pitch black (complete darkness) are often rewarded with deeper sleep and more energy during the day. Darkness is not the absence of light, but the presence of rest.

If you are looking for an apartment that already has high-quality roller shutters or is located in a quiet, low-light environment to guarantee optimal lighting conditions in the bedroom , Loft offers the right search functions and properties.

Glossary

• Bedroom lighting conditions: The totality of all light sources (natural and artificial) in the bedroom that affect sleep quality.
• Melatonin: The "sleep hormone" produced in the pineal gland. Its release is directly dependent on dark lighting conditions in the bedroom .
• Lux: The unit of measurement for illuminance. For healthy sleep, the value in the room should be below 1 lux.
• Light pollution: The brightening of the night sky by artificial light sources, which negatively affects the lighting conditions in bedrooms in cities.
• Circadian rhythm: The human body's internal clock, which controls the sleep-wake cycle and is primarily synchronized by light and darkness.