How Light and Temperature Mix with Sleep
Summertime brings beach days and pool outings, but also warmer weather and longer days. In fact, the longest day of the year lands on June 21st! Do these long days with increased temperatures impact sleep? It’s probably no surprise that the answer is yes.
In this article, we’ll explore how temperature and light mix with sleep, and how you can create a bedroom environment with the ideal sleeping temperature and optimal light for maximum sleep.
How Light Affects Sleep
Our internal clocks are set based on the rising and setting of the sun. This is known as our circadian rhythm, and it’s the basis for why we feel awake and tired at the same times every day. The human race had no issues with sleep schedules until the invention of the light bulb. From then on, our ability to lengthen “daylight” meant the end of easy, natural sleeping. Our bodies produce melatonin as it grows dark outside, and our body slowly eases into sleepiness. But with lights in our houses, as well as light emitted from our mobile devices, our bodies have a hard time determining when it’s truly bedtime.
Research continues to show that exposure to light in the evening—especially artificial or blue-spectrum light—can significantly delay melatonin production and disrupt sleep cycles (Gooley et al., 2009).
What about Temperature?
Temperature also plays a role in our natural process of going to sleep. As our brains produce melatonin, our bodies respond by becoming (on average) a degree or two colder. Scientists have learned that trying to sleep when you’re too cold or hot can be difficult because our bodies crave a certain ideal temperature for sleep.
Recent studies suggest that the ideal bedroom temperature for optimal sleep quality lies between 60°F and 67°F, though some sources extend the upper end of that range slightly to 77°F depending on individual variation and age-related needs (Psychology Today, 2025; The Brighter Side of News, 2025).
So, as night falls, our brains cue us to feel tired and the body temperature decreases as the metabolism slows. That means it should be easy enough to enjoy a good night’s sleep, yet millions of us don’t. Why not? Scientists point to our love of all things electronic.
What Is “Lux” and How Does It Affect Sleep?
Light is never just “light.” It has lux, lumen, and wavelengths, and each of them can interfere with good sleep. Let’s look at lux and lumen. The latter is “a measurement of light intensity or brightness, also known as radiance, at the source of the light itself.” On the other hand, lux uses lumen values but also looks at the impact that light has on the space around it.
Standard lux readings in a home are around 300-500, but in the evening and during the hours before bed, it should be less than 180. After you turn out your lights, it should not be more than 5 lux. In fact, studies show that even light levels above 3 lux can negatively affect melatonin and increase chronic health risks such as diabetes and insomnia (University of Manchester, 2022).
Blue Light and Bed Time
Blue light, according to Harvard Medical School, “is beneficial during daylight hours because they boost attention, reaction times, and mood—seem to be the most disruptive at night… While light of any kind can suppress the secretion of melatonin, blue light at night does so more powerfully” (Harvard Health Publishing, 2023).
It makes sense that something promoting alertness would interfere with melatonin, the hormone responsible for winding the body down before bed. Our smartphones and electronic devices emit blue light, making it harder than ever to wind down naturally.
Fortunately, there are a few ways you can avoid the problems associated with blue light. Many modern smartphones include blue light filters or night modes, and there are apps or screen protectors to reduce blue light exposure. The best practice is still to power down all electronics at least one hour before bed, which also supports mental relaxation before sleep.
Emerging research even suggests that the timing and dosage of blue light can be leveraged positively in older adults to reset sleep rhythms—so it’s not all bad, just misused in the wrong context (ScienceDaily, 2025; New York Post, 2025).
Ways to Sleep Better with Summer Light and Temperatures
Finding great sleep even amidst summer conditions is challenging, but we have a few suggestions that can help:
- Blue Light Blocking Glasses: If you’re looking for a way to block blue light without having to give up your electronics in the evening, check out some of our favorite blue light blocking glasses.
- Dual Climate Control Systems: Struggle with finding a great temperature that both you and your bed partner can agree on? A dual climate control system for your bed is here, and we love it!
- Eye Masks: If those late sunsets and early sunrises are keeping you up, a comfortable and effective eye mask may be just the answer you’re looking for.
- Mattress Cooling Systems: Can’t quite seem to get cool no matter how high you keep the fan at night? Check out our favorite mattress cooling system!
Understanding how light and temperature affect your sleep is the first step—knowing how to act on that information is where SleepScore comes in.
How Can SleepScore Help
With the SleepScore app and ecosystem, you can:
- Track bedroom conditions: Get real-time feedback on your sleep environment, including bedroom temperature and light exposure.
- Access personalized insights: SleepScore’s non-contact sleep tracking provides tailored recommendations to improve your bedroom setup based on your actual sleep patterns.
- Monitor seasonal shifts: As summer temperatures rise or winter darkness sets in, SleepScore helps you adapt your routines accordingly for optimal rest.
- Shop scientifically backed solutions: Whether it’s blue light glasses, cooling mattress systems, or blackout curtains, our curated product recommendations are selected to directly target the factors disturbing your sleep.
Every feature is backed by science and designed to empower your sleep health—one night at a time. Discover how optimizing your environment can help you get deeper, more restful sleep year-round with SleepScore.
Sleep Well!
Sources
- Gooley, J. J., et al. (2009). Effect of Light on Human Circadian Physiology. National Institutes of Health. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717723
- Psychology Today. (2025). The Key Role of Temperature in Sleep Quality. https://www.psychologytoday.com/us/blog/the-modern-brain/202503/the-key-role-of-temperature-in-sleep-quality
- The Brighter Side of News. (2025). Researchers Discover the Ideal Temperature for a Healthier and More Regenerative Sleep. https://www.thebrighterside.news/post/researchers-discover-the-ideal-temperature-for-a-healthier-and-more-regenerative-sleep
- University of Manchester. (2022). Making Light Work: Recommendations for Healthy Lighting. https://blog.policy.manchester.ac.uk/sci-tech/2022/06/making-light-work-recommendations-for-healthy-lighting
- Harvard Health Publishing. (2023). Blue Light Has a Dark Side. https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side
- ScienceDaily. (2025). Morning Blue Light Therapy Improves Sleep and Daily Activity in Older Adults. https://www.sciencedaily.com/releases/2025/02/250225122145.htm
- New York Post. (2025). Blue Light Can Actually Help Older Adults Sleep – But Only If They’re Exposed at the Right Time of Day. https://nypost.com/2025/03/03/health/blue-light-can-help-older-adults-sleep-if-exposure-is-at-a-certain-time
- Sleep.org. (n.d.). The Ideal Temperature for Sleep. https://sleep.org/articles/temperature-for-sleep
- S+ ResMed. (n.d.). Darkness Matters – How Light Affects Sleep. http://sleep.mysplus.com/library/category2/article1.html
- Sleep Foundation. (2024). Study Finds Wavelength of Light, Not Color, Impacts Sleep. https://www.sleepfoundation.org/sleep-news/study-finds-wavelength-of-light-not-color-impacts-sleep