How does light affect your sleep?

natural light beaming through a room

Anyone who has struggled to ignore a pesky streetlight peeking through the curtains – or that battery light across the room that won’t stop flashing – knows that light can affect sleep. But those effects run deeper than many of us realize.  

Light plays a key role in your body’s internal clock, not just at night but throughout the 24-hour cycle. Different kinds of light can affect your body differently at certain times of day. Understanding this relationship—and the actions you can take to manage—can make a big difference to your sleep. 

Blue light during the day 

Sunlight plays a pivotal role in synchronizing your circadian rhythm with the day-night cycle. Exposure to daylight can not only boost your energy in the afternoon, but it can also help set on track to good quality zZz’s at night, according to some research.1  

The reason: Daylight, especially in the morning, cues your body to release cortisol, the hormone that preps your body to wake up and be alert, while suppressing melatonin, your sleep hormone. On the flip side, the absence of light triggers your body to make melatonin and suppress cortisol.  

So if you’re spending most of your day indoors and getting limited natural light, you might be pushing that mechanism out of alignment, making it hard to get to sleep when you need to. To put your body clock back on schedule, try to expose yourself to bright light during the day—either by going outside or, if that’s not possible, investing in a bright artificial light designed for that purpose. 

Warm light at night 

While scrolling through your social feeds or catching up on the latest Netflix hit might feel light a good wind down, this habit might actually be the reason you’re not getting good-quality sleep.  

This is because your phone, computer, TV and other electronics emit short-wavelength, high-energy light at the blue end of the spectrum, effectively mimicking the sun. In the day, these wavelengths can be helpful, as they promote wakefulness, a positive mood, good concentration and performance.  

But prolonged exposure to blue light right before bedtime can have a negative effect, stimulating your system at the wrong time of day and inhibiting the release of melatonin. Together, these effects can make it hard for you to fall asleep and may decrease your overall sleep quality. 

Tips to get more daylight 

  1. Rise and shine with the sun: Aim to wake up and expose yourself to natural light as early as possible. Open your curtains or step outside for some fresh air or a morning walk to kick-start your body’s wakefulness response. 
  1. Get outdoors during the day: Take breaks during the day to spend time outside, especially in the morning and early afternoon. And try activities like walking, exercising or having lunch outdoors to soak up the natural light. 
  1. Optimize your workspace: Position your desk near windows to allow natural light to flood your workspace. 
  1. Embrace nature during weekends: Engage in outdoor activities like hiking, gardening or simply relaxing in the sun for a few hours on your days off. This will not only expose you to more daylight but also help you unwind and even reduce stress. 
  1. Lighten up your home: Try to keep your curtains open during the day to allow sunlight into your living space. If privacy is a concern, consider using sheer curtains that still let some daylight through. 

 Tips to minimize blue light at night 

  1. Limit screen time before bed: Make yourself a digital curfew (at least an hour before bedtime) for your phone and other electronics. Instead, engage in relaxing habits like reading a book, listening to music or meditation. 
  1. Use blue light filters: If you need to use your electronics late in the evening, consider investing in blue light filters or night mode settings that reduce the amount of blue light emitted.  
  1. Wear blue light-blocking glasses: Blue light-blocking glasses or lenses can be worn in the evening to filter out the harmful blue light emitted by screens. These glasses can help maintain the natural release of melatonin and promote better sleep. 
  1. Opt for warm, dim lighting: In the evening, switch to warm, low-intensity lighting in your home. Replace bright, cool-toned bulbs with warmer lights or use dimmer switches to create a relaxed setting that signals your body it’s time to wind down. 
  1. Establish a sleep-friendly bedroom environment: Make sure your bedroom is dark and free from blue light sources. Use blackout curtains, cover LED displays and remove electronic devices. 

Read next: 5 tips to balance cortisol for better sleep

About Gabby 

Gabby is a Nutritionist with a master’s degree in strategic communications. She loves using her nutrition-fluency with storytelling to encourage positive change. Before Persona, she worked at a mental health clinic helping clients manage stress, anxiety and other mental health issues through diet.    

Gabby is just one of the many experts at Persona who are here to accelerate your wellness journey. If you have questions about nutrition or your personalized program, reach out now or book a free appointment with Gabby or another of our amazing nutritionists.   

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.      

This information is not intended as a substitute for the advice provided by your physician or other healthcare professional, or any information contained on or in any product label or packaging. Do not use the information from this article for diagnosing or treating a health problem or disease, or prescribing medication or other treatment. Always speak with your physician or other healthcare professional before taking any medication or nutritional, herbal, or homeopathic supplement, or using any treatment for a health problem. If you have or suspect that you have a medical problem, contact your health care provider promptly. Do not disregard professional medical advice or delay in seeking professional advice because of something you have read in this article.        


  1. Blume C, Garbazza C, Spitschan M. Effects of light on human circadian rhythms, sleep and mood. Somnologie (Berl). 2019;23(3):147-156. doi:10.1007/s11818-019-00215-x 

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