← Huberman Lab

Journal Club with Dr. Peter Attia | Effects of Light & Dark on Mental Health & Treatments for Cancer

Episode 160 Jan 22, 2024 3h 4m 17 insights
In this journal club episode, my guest is Dr. Peter Attia, M.D., a Stanford and Johns Hopkins-trained physician focusing on healthspan and lifespan and the host of The Drive podcast. We each present a peer-reviewed scientific paper chosen because it contains novel, interesting, and actionable data. First, we discuss a paper on how bright light exposure at sunrise and throughout the day and dark exposure at night independently improve mental health and can offset some of the major symptoms of mental health disorders such as depression and anxiety. Then, we discuss an article that explores a novel class of immunotherapy treatments to combat cancer. We also discuss some of the new data on low-calorie sweeteners and if they are safe. This episode should be of interest to listeners curious about maximizing their vitality and longevity and to anyone seeking science-supported ways to improve mental health and lifespan. Read the full shotes for this episode at hubermanlab.com.
Actionable Insights

1. Optimize Daily Light Exposure

Actively seek bright light exposure to your eyes throughout the entire day, ideally from sunlight, as this has independent and additive positive effects on mental health and can reduce symptoms of mental health disorders. If you cannot get enough daytime light, prioritize maximizing darkness at night.

2. View Morning Sunlight

View low solar angle sunlight in the early part of the day for about 10 minutes or more, without sunglasses, to phase advance your circadian clock, which helps you want to go to bed and wake up earlier the next day. This also increases the amplitude of your morning cortisol spike, which is beneficial for overall circadian rhythm.

3. Minimize Nighttime Light Exposure

Get as much darkness exposure at night as possible, as this has independent and additive positive effects on mental health. Minimizing light at night is especially crucial for individuals with bipolar disorder, PTSD, major depressive disorder, and to reduce the probability of self-harm and psychotic symptoms.

4. View Evening Sunlight

View low solar angle sunlight in the late afternoon or evening as often as possible to phase delay your circadian clock, which helps stabilize your sleep-wake cycle. This practice can also partially offset the negative effects of artificial light exposure at night.

5. Avoid Nighttime Screen Brightness

Minimize direct light exposure to your eyes from phones or tablets at night, as high light intensity (e.g., 500-1000 lux) over time can disrupt circadian rhythms and negatively impact mood. While blue light filters help, the overall brightness and content consumed also matter.

6. Prioritize Morning Light if Missed

If you miss a day of optimal light exposure, aim to get twice as much morning light the next day, as the circadian clock integrates photon exposure over a two to three-day period.

7. Strategic Sunglass Use

Wear sunglasses in the middle of the day when the sun is high, but avoid using them in the early and later parts of the day to allow sufficient photons to reach your eyes for circadian rhythm regulation, unless safety reasons (e.g., driving into the sun) require them.

8. Optimize Indoor Lighting

Recognize that most indoor environments are not bright enough to positively impact mood and circadian rhythms; therefore, make a conscious effort to get outside. At night, dim indoor lights and ideally use lower-set, red-spectrum lights to minimize disruption.

9. Avoid Blue Blockers During Day

Do not wear blue-blocking glasses during the daytime, as this is counterproductive to getting the necessary bright light exposure that triggers mood-enhancing mechanisms and helps set your circadian clock.

10. Use Corrective Lenses for Sunlight

It is acceptable to wear eyeglasses or contact lenses while viewing sunlight for circadian rhythm regulation, as these corrective lenses focus light onto the retina rather than filtering or scattering it like windows or windshields.

11. Manage Sleep Trackers Mindfully

Use sleep trackers as a tool for insight and behavioral change, but be mindful of the ‘Hawthorne effect’ and avoid letting a poor sleep score negatively dictate your perceived energy or mood for the day. View scores as averages and indications for adjustment.

12. Minimize Nighttime Waking Disruptions

If you wake up in the middle of the night, avoid looking at the time, as this can be disruptive to falling back asleep and negatively impact your perceived energy the next day.

13. Consider Red Light for Nighttime

Use red light bulbs or dim red lights in the evening to minimize light exposure at night, which can be beneficial for sleep and mood. Avoid placing t-shirts over lamps due to fire hazards.

14. Be Cautious with Artificial Sweeteners

Exercise caution and use limited amounts of artificial sweeteners, as research suggests they may muck around with brain chemistry, gut chemistry, and metabolism, potentially stimulating appetite or causing cephalic insulin responses in some individuals.

15. Promote Circadian Rhythm in Hospitals

For patients in hospitals, especially those with brain injuries or strokes, ensure they are near a window and actively control their sleep-wake cycle as much as possible to counteract the detrimental lighting environments and prevent conditions like ICU psychosis.

16. Support Immune Health with Age

Maintain a normal circadian schedule and prioritize sufficient rest to keep the immune system as healthy as possible as you age, as a robust immune system plays a critical role in combating infections and potentially reducing cancer susceptibility.

17. Prevent Melanoma with Sun Protection

Avoid sunburns by being mindful of the UV index, wearing appropriate cover, or using safe mineral sunscreens. This is crucial for reducing the risk of melanoma, with early and repeated sunburns posing a particular risk.