Sleeping seems like a simple thing to do: turn off the light, close your eyes, and rest. However, a study made by Northwestern Medicine and published in Proceedings of the National Academy of Science (PNAS) shows that even moderate light can seriously affect your health.
Although many people sleep with a lamp on, a television glowing, or streetlight coming through the window. According to this research, that nighttime light exposure can impact the heart, metabolism, and overall sleep quality. So, let’s see why.
Nighttime light affects your heart and rest
When we sleep in total darkness, our body enters a recovery state. During the night, the parasympathetic nervous system helps slow your heart rate and allows your body to relax deeply. This process is crucial for physical repair and overall health.
However, the Northwestern Medicine study proves that moderate light in the room changes this situation. Although the person doesn’t wake up, the body is not completely relaxed because light activates the autonomic nervous system and keeps the body in a mild state of alertness. As a result:
- The heart beats faster.
- The force of the heartbeats increases.
- Blood circulation speeds up.
- Deep, restorative sleep is reduced.
According to the research, even just one night sleeping with the light on can alter your normal sleep physiology. This means the body does not enter the fully restorative state needed to maintain cardiovascular and hormonal health.
The impact of light in your metabolism and weight
The study also points out that nighttime light affects your heart, but also your metabolism. During nighttime, your body regulates glucose, the sugar used for energy.
When exposed to light during the night, this regulation can be disrupted. The research found that nighttime light increases the risk of insulin resistance. This happens when muscle, liver, and fat cells do not use glucose efficiently. As a result, the pancreas must produce more insulin to keep blood sugar levels balanced.
Over time, this can raise blood sugar levels and increase the risk of developing type 2 diabetes. The study also reports that people who sleep with moderate ambient light are more likely to experience overweight and obesity compared to those who sleep in darkness.
Darkness is the key to health
To protect your brain and the rest of your body, sleeping in complete darkness is paramount because our brain needs clear signs that it’s nighttime to activate deep rest processes. When light is present, even if it is dim, those signals are disrupted.
So, closing curtains, lowering blinds, and turning off nearby lights are important strategies to support heart health, hormonal balance, and metabolic regulation.
Practical steps to sleep in complete darkness
To know how to protect your health while sleeping, here are some ideas:
- Turning off all direct lights before going to bed.
- Avoiding white or blue light in the bedroom.
- Using dim amber or red lights if lighting is needed for safety.
- Closing curtains or blinds to block outside light.
- Wearing an eye mask if external light cannot be controlled.
So…
By protecting your sleep environment, you are not just getting a more comfortable night’s rest, but also actively supporting your long-term health. Will you have a go at these steps and rest in complete darkness tonight? Maybe you will find it difficult the first few days if you are used to sleeping with some kind of light, but trust me it’s worth it.