Stanford neuroscientist Andrew Huberman is a strong advocate for exposing oneself to daily sunlight, frequently discussing its benefits on his popular podcast. Sunlight exposure plays a crucial role in maintaining the body’s circadian rhythm, according to experts. Spending an hour outdoors in the sunlight is ideal, but a minimum of 30 minutes is recommended.
Each morning, I make it a point to go for a walk outside without wearing sunglasses, as recommended by Andrew Huberman. Huberman, the host of the highly popular “Huberman Lab” podcast and a neuroscientist at Stanford University, emphasizes the importance of sunlight exposure in the morning. In a recent post on Twitter, now known as X, Huberman identified morning sunlight as one of the six fundamental pillars of good health, alongside daily physical activity, nutrition, stress management, healthy relationships, and quality sleep. He believes that circadian health, which refers to the 24-hour internal clock in the human brain, is the foundation of overall well-being.
Since I started this morning walk routine, which typically lasts between 10 and 30 minutes for me, I have experienced immediate positive results. I feel more alert and awake right after the walk. To be honest, I also feel happier and less irritable. The morning grogginess that I used to feel upon waking has significantly decreased, and some days it even disappears entirely. I find myself more motivated during the day, and my Fitbit confirms that I am sleeping better. Although I cannot say for sure if these improvements are directly linked to my new routine, I was curious to understand the science behind it. I wanted to know if it was a placebo effect or some other factor, or if, as Huberman claims, exposing my eyes to daylight was truly responsible.
As it turns out, Huberman is not the only expert who swears by the benefits of outdoor light. Mariana G. Figueiro, a professor and director of the Light and Health Research Center at the Icahn School of Medicine at Mount Sinai, believes that outdoor light is just as crucial as diet and exercise for a high quality of life. Figueiro, who focuses on researching the effects of light on human health, explains that the brightness of daylight and the darkness of night are essential for regulating our circadian rhythms. Without exposure to light, especially in the morning, our internal clocks may drift by about 10 minutes each day. For instance, spending weeks in a completely dark environment can disrupt our circadian rhythms to the point where our brains think that day is night and night is day. However, exposure to daylight helps reset our biological clocks every 24 hours, keeping them on track.
People are generally aware of the role sunlight plays in vitamin D production, which involves direct contact between sunlight and the skin. However, for circadian regulation, Figueiro explains that it is the light that reaches the back of our eyes from the environment that matters, even if we are sitting in the shade. While artificial lighting can provide some benefits, indoor light is typically not bright enough. On a sunny day, we can receive 100,000 lux, a unit of measure for light intensity, while a cloudy morning still offers around 5,000 lux. In comparison, average indoor lighting only provides around 300 lux. Figueiro highlights that daylight is optimal for synchronizing our biological clocks because it provides the right amount and quality of light at the right time.
To maintain proper circadian regulation, it is not just morning light but also evening darkness that is necessary. When there is an imbalance between light and darkness, it leads to “circadian disruption.” This disruption can result in issues such as poor sleep, reduced cognitive performance, and daytime drowsiness. Prolonged periods of circadian disruption have been linked to a weaker immune system and an increased risk of cardiovascular disease, diabetes, obesity, and cancer. In a study conducted in 2014, Figueiro and her colleagues found that providing specific lighting to Alzheimer’s patients in nursing homes improved their sleep, reduced depression, and minimized agitation over a period of six months, despite the progression of their disease.
Figueiro recommends a minimum of one hour of daylight exposure per day, ideally in the morning. For her, incorporating sunlight into her morning commute, whether by walking or driving, without wearing sunglasses, ensures maximum light intake. Morning sunlight can be obtained through activities such as walking the dog, having breakfast on the porch, or taking outdoor meetings. If you spend more time outdoors, it is advisable to use sunscreen for skin protection, as it does not hinder light intake through the eyes. When going outside is not possible, you can still benefit from sitting in front of a bright window. Breaking up your outdoor time, such as spending half an hour in the morning and another half hour at lunch, can also be beneficial, but morning light is especially important for regulating your internal clock.
While natural outdoor light is best, artificial lighting can be used as a supplement, especially when spending most of the day indoors in a darker environment. Figueiro explains that indoor lighting cannot match the intensity of daylight and suggests adding two to four table lamps to your workspace. For example, positioning two lamps on either side of your computer with bulbs that emit at least 3,000 lumens, as indicated on the packaging, can help supplement indoor lighting. The key is to ensure that the light is bright but not directly shining into your face, such as by using a lantern-style shade to diffuse the light. Light therapy boxes designed to simulate outdoor light and treat seasonal affective disorder can also be used. However, it is important to consult a healthcare provider before using them. Mayo Clinic recommends using the light therapy box for about 20 to 30 minutes within the first hour of waking up.
Even just ten minutes of morning sunlight can have a positive impact if that’s all you can manage, but consistency is key. Figueiro emphasizes the importance of regularity, as the biological clock thrives on a consistent schedule. It is crucial to make it a daily habit at around the same time.
