The viral ‘Dutch method’ sleep hack gets one important thing wrong

Sleeping with the curtains open? Why the ‘Dutch Method’ isn’t great for your sleep

I recently came across a new sleep hack that has gone viral: 'The Dutch Method.' According to several articles — including one in the British quality newspaper  The Guardian — and various posts on social media, a typically Dutch habit might surprisingly be good for your sleep: sleeping with the curtains open.

The idea sounds simple and appealing. The Dutch are known for their homes with large windows and open curtains. According to some sleep experts, it might therefore be smart to leave your curtains open at night so that morning light can enter your room and help regulate your biological clock.But this is where something goes wrong.

What is The Dutch Method?

The method consists of three simple rules:

• Leave the curtains open at night

• Make sure morning light can reach your bedroom

• Don’t use blackout curtains

  
  

At first glance this seems logical. Morning light is indeed important for your biological clock. However, this method confuses two completely different things: Morning light is good. Night-time light is not.

The problem with light at night

In the evening and at night it is important that it gets dark. Darkness allows your body to produce melatonin, the hormone that makes you feel sleepy. Light disrupts this process. A frequently cited study by researchers from Harvard University and Brigham and Women's Hospital examined what happens when people are exposed to normal room light in the evening (less than 200 lux).

The results were quite striking:

• In 99% of participants, melatonin production started later

• The duration of melatonin production became about 90 minutes shorter

• During the night, melatonin was sometimes suppressed by more than 50%

  
  

A systematic review of scientific studies on light and circadian rhythms shows that even very low light levels (5–10 lux) — the level of dim night light, such as a streetlamp or urban light pollution — can already cause a subtle shift in the biological clock.

Light is crucial for sleep

When light reaches the eye, it sends signals to several areas of the brain that determine whether we should feel alert or sleepy. This makes light one of the most important external factors regulating sleep.

The process also controls the production of melatonin, the hormone that makes us sleepy. But there’s a catch: light suppresses melatonin, making it harder to fall asleep and stay asleep.

The Dutch habit of leaving curtains open actually has nothing to do with sleep science. It is rooted in culture and history (Calvinism, transparency, and social control). Many Dutch people grew up with it. Moreover, it usually refers to leaving the living room curtains open. I know very few Dutch who apply this habit in the bedroom as well.

Not a useful sleep hack

The Dutch Method is not a useful sleep hack. If you want to wake up naturally in the morning, you could use a wake-up light or automatic curtains. That way you give your biological clock the best of both worlds:the darkness of night, which makes you sleepy, and the morning light, which helps you wake up alert.

The first time I used a wake-up light, I had a dream shortly before the alarm went off that I was standing on the deck of a ship watching the sunrise. I woke up in the middle of winter with a summer feeling. It also showed that my eyes had already started detecting the light while I was still asleep.