How Light Impacts Our Stress Response System and More

How Light Impacts Our Stress Response System and More

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Is it possible for light to have an impact on the body's nervous system? Does light create stress? In this article we help answer those questions, and cover why a balance between the parasympathetic and sympathetic nervous systems is vital to our health and wellbeing.

To start, you may wonder what these two systems are and why a healthy balance is important. To help answer those questions, let’s begin with a general overview of each system. 

Autonomic Nervous System

The autonomic nervous system (ANS) is a network of nerves throughout the body that controls unconscious processes like breathing and heart rate. This system is critical to our survival and remains continuously active, even during sleep. Its main purpose is to connect the brain to the body’s internal organs.[1] 

The autonomic nervous system is part of the peripheral nervous system, one of two subsystems from our overall nervous system. The ANS has two divisions, the parasympathetic division and sympathetic division. These two divisions are very different, yet very important to one another. The parasympathetic division is responsible for all the processes in our body that help us ‘rest-and-digest’, where the sympathetic division is responsible for all of our ‘fight-or-flight’ responses. Another way to describe them, is that the sympathetic nervous system activates body processes, where the parasympathetic deactivates, or lowers them. Balance among these two systems is key to our overall health and wellbeing.

Stress Response

Most of us spend more time with the sympathetic nervous system active because of stress. We might not even know the stress is there, but our bodies do and react by releasing stress hormones. This results in a repeated activation of our stress response system that takes a toll on our bodies over time. However, not all stress should be considered negative. In fact, the human body is designed to experience stress and react to it as part of our ‘fight-or-flight’ response system. When we experience a new or challenging situation, our bodies produce physical and mental responses that alert and help us adjust. While this shows that stress can be positive, it can become a problem when stressors continue without relief, or periods of relaxation. If we are unaware that the body is continuously under stress, we lose the balance that is needed between nervous systems. This results in spending too much time with our ‘fight-or-flight’ system activated. 

Light Can Be a Stressor 

It’s important to be aware that not all stress is physical, or results from an incident. Our bodies can be impacted by the environmental stressors that surround us every day. Visible light is an example of an environmental stressor that we aren’t always aware of. [2] Light is responsible for activating critical hormones that help us stay awake and fall asleep. Cortisol is a hormone that helps our body be alert and stay awake during the daytime. Melatonin is another hormone that works similar to cortisol, but instead, relaxes us so we can sleep during the night. Studies have shown that exposure to certain types of light during specific periods of the day can impact the production of both cortisol and melatonin.

Exposure to Red and Blue Light 

It's important to note that almost all variations of light at night can impact our sleep. But in general, blue light seems to have the greatest impact because of its ability to stimulate the production of cortisol and disrupt the secretion of melatonin. To learn more about blue light and sleep click here.

Red light on the other hand, has less of a negative effect on melatonin when compared to blue light. [3] This suggests that red light could be beneficial in helping maintain healthy melatonin levels during evening hours. Red light does not stimulate the production of melatonin, but when compared to blue light, is much less disruptive. As we covered earlier, melatonin is a hormone that helps us relax and sleep better, which aids in the activation of the parasympathetic nervous system.

It is beneficial for our wellbeing to maintain a healthy balance between the sympathetic and parasympathetic response states. The use of red light may aid in helping us relax, promoting activation of the parasympathetic system.   

How Joovv Ambient Mode Can Help 

Ambient Mode is available on our latest generation of devices. While not a treatment mode, this feature was thoughtfully designed for use in the morning and evening to replace standard room lighting with a soothing red glow. 

When using this mode to light a room, you can still enjoy your favorite nightly activities, without taking in as much blue or white light from traditional light fixtures and screens. This helps support relaxation and mitigates negative light stress to help provide a smoother transition into sleep. Ambient Mode is also a more natural way to transition from sleep to waking. 

When using Ambient Mode with the Joovv Solo 3.0, or Mini 3.0, it is ideal to face the device towards a wall to reflect the light and create a diffused effect. The same can be done with the Joovv Go 2.0, or you can point the LEDs upward, as the device is smaller in size, requiring less diffusion. 


Light in our everyday environment can keep the body's stress response system active. The use of red light after dark can help maintain our natural circadian rhythms and bring balance to our autonomic nervous system. Using red light as an alternative light source to blue light has been shown to be less disruptive in melatonin secretion. In general, it's best to avoid bright light after dark, and ideal to keep your surroundings as dark as possible 2-3 hours before bedtime. In today’s world, that is easier said than done - and why red light can be a great alternative solution to promote relaxation and good restful sleep.  



[1] Amthor FR. Chapter 18: Autonomic Nervous System: Sympathetic, Parasympathetic, & Enteric. In: Amthor FR, Theibert AB, Standaert DG, Roberson ED. eds. Essentials of Modern Neuroscience. McGraw Hill; 2020.

[2Petrowski K, Bührer S, Albus C, Schmalbach B. Increase in cortisol concentration due to standardized bright and blue light exposure on saliva cortisol in the morning following sleep laboratory. Stress. 2021 May;24(3):331-337. doi: 10.1080/10253890.2020.1803265. Epub 2020 Aug 10. PMID: 32723201.

[3Figueiro MG, Rea MS. The effects of red and blue lights on circadian variations in cortisol, alpha amylase, and melatonin. Int J Endocrinol. 2010;2010:829351. doi: 10.1155/2010/829351. Epub 2010 Jun 24. PMID: 20652045; PMCID: PMC2905913.

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