January 22, 2024 • 3hr 8min

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

Huberman Lab

In this journal club episode, Dr. Andrew Huberman and Dr. Peter Attia each present and discuss a scientific paper they find interesting and important. Dr. Huberman covers a paper on how light exposure during the day and darkness at night independently impact mental health. Dr. Attia discusses a landmark paper on the checkpoint inhibitor immunotherapy drug ipilimumab for treating melanoma. The discussion provides insights into circadian biology, mental health, cancer immunology, and how to critically analyze scientific papers.

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Key Takeaways

Getting bright light exposure during the day and dark exposure at night have independent and additive positive effects on mental health and can reduce symptoms of various mental health disorders
Viewing sunlight within 30-60 minutes of waking, again in the late afternoon/evening, and getting bright light throughout the day is ideal for setting circadian rhythms and improving mood
Darkness at night for 8+ hours should be viewed as a treatment for mental health, especially for conditions like bipolar disorder
Checkpoint inhibitor immunotherapy drugs like ipilimumab have shown promise in treating some cancers by "taking the brakes off" the immune system to attack cancer cells
While these immunotherapy drugs have only increased overall survival by about 8-10% so far, they represent an important new approach to cancer treatment
Melanoma has been a key focus for immunotherapy because it tends to have more mutations that can be recognized by the immune system
Autoimmune side effects from immunotherapy drugs can be severe but may correlate with better treatment responses in some cases

Introduction

In this journal club episode, Dr. Andrew Huberman and Dr. Peter Attia each present and discuss a scientific paper they find interesting and important. Dr. Huberman covers a paper on how light exposure during the day and darkness at night independently impact mental health. Dr. Attia discusses a landmark paper on the checkpoint inhibitor immunotherapy drug ipilimumab for treating melanoma. The discussion provides insights into circadian biology, mental health, cancer immunology, and how to critically analyze scientific papers.

Topics Discussed

Light, Dark & Mental Health (7:14)

Dr. Huberman presents a paper examining how light exposure during the day and darkness at night independently affect mental health in over 85,000 people. Key points include:

There is a long-standing interest in the relationship between light and mental/physical health, including seasonal affective disorder
Bright light exposure, especially in the morning, has been used to treat seasonal affective disorder
The biological mechanisms involve intrinsically photosensitive retinal ganglion cells in the eye that respond to light and send signals to regulate circadian rhythms and mood
These cells respond to both very bright light and contrast between short and long wavelengths of light

"There seems to be, based on the conclusions of this new study, a powerful and independent role of both daytime light exposure and nighttime dark exposure for mental health." - Dr. Andrew Huberman

Outdoor vs. Indoor Light, Cataracts, Sunglasses (11:16)

The discussion covers important points about light exposure:

Outdoor sunlight can provide 100,000-300,000 lux, while bright indoor environments are typically only 4,000-6,000 lux
Even on cloudy days, outdoor light is much brighter than indoor light
Low solar angle sunlight in the morning and evening is key for setting circadian rhythms
Sunglasses should be avoided in early morning/evening to allow proper light exposure, but can be used midday to protect eyes

Tools: Sunrise & Sunsets, Circadian Rhythm; Midday Light (16:17)

Dr. Huberman explains key light exposure recommendations:

View low solar angle sunlight for 10+ minutes within 30-60 minutes of waking
Get another 10+ minutes of sunlight exposure in the late afternoon/evening
Get as much bright light exposure as safely possible throughout the day
Viewing evening sunlight can partially offset negative effects of artificial light at night

"I suggest on non-cloudy days, we'll call them that, people get 10 minutes or so of sunlight in their eyes in the early part of the day, another 10 minimum in the later part of the day, as much sunlight in their eyes as they safely can throughout the day." - Dr. Andrew Huberman

Tools: Night & Light Exposure; Waking Before Sunrise (24:55)

The discussion covers nighttime light exposure:

Darkness at night for 8+ hours should be viewed as a treatment for mental health
Avoid very bright light exposure at night, but brief exposure (e.g. bathroom light) is not a major concern
Red lights or dim lighting can be used at night to minimize circadian disruption
For those who wake before sunrise, turn on bright indoor lights and then get outdoor light exposure once the sun rises

Article #1, Light/Dark Exposure & Mental Health (31:05)

Dr. Huberman discusses key findings from the paper on light exposure and mental health:

Greater light exposure during the day was associated with lower risk of psychiatric disorders
Greater light exposure at night was associated with higher risk of psychiatric disorders and poorer mood
The effects of daytime light exposure and nighttime darkness were independent and additive
People with bipolar disorder seemed especially sensitive to nighttime light exposure

"Darkness for 8 hours every night should be viewed, in my opinion, as a treatment for bipolar disorder. Not the only treatment, but it's also clear that we should all be avoiding really bright, extensive, really bright nighttime light exposure." - Dr. Andrew Huberman

Nighttime Light Exposure; Sleep Trackers & Belief Effects (1:08:14)

The discussion covers additional points on nighttime light and sleep:

Even dim moonlight or candlelight is much less bright than daytime light
Phone/tablet screens at night can be quite bright, around 500-1000 lux
Sleep trackers can create nocebo effects if people see "bad" sleep scores
Focus on averages and trends with sleep tracking rather than individual nights

Article #2, Immune System & Cancer (1:39:53)

Dr. Attia presents a landmark paper on the checkpoint inhibitor immunotherapy drug ipilimumab for treating melanoma. Key points include:

The immune system has evolved to detect foreign pathogens while avoiding attacking the self
Cancer evades the immune system through various mechanisms like secreting factors that suppress immune response
Checkpoint inhibitors like ipilimumab work by "taking the brakes off" the immune system to attack cancer cells
This study showed ipilimumab improved median and overall survival in patients with advanced melanoma

"I still believe that immunotherapy is probably the most important hope we have for treating cancer. And while I think we're still only scratching the surface of it, so, collectively, the overall survival increase for patients with metastatic solid organ tumors is about 8% better than it was 50 years ago. And virtually all of that has come from some form of immunotherapy I think is promising." - Dr. Peter Attia

Checkpoint Inhibitors, CTLA-4 (2:00:09)

Dr. Attia explains the mechanism of checkpoint inhibitors:

CTLA-4 is a receptor on T cells that acts as a "brake" on immune response
Ipilimumab blocks CTLA-4, allowing T cells to mount a stronger attack against cancer cells
This approach is different from previous immunotherapies that tried to stimulate the immune system
Melanoma was an early target because it tends to have more mutations that can be recognized by the immune system

Anti-CTLA-4 Study Drug (Ipilimumab), Melanoma (2:06:45)

Key details of the ipilimumab study are discussed:

The study included patients with advanced melanoma who had progressed through other treatments
It compared ipilimumab alone, ipilimumab + a peptide vaccine, and the peptide vaccine alone
The primary outcome was overall survival
Ipilimumab improved median survival from about 6 months to 10 months

Adverse Events; Autoimmunity (2:40:32)

The discussion covers side effects of checkpoint inhibitors:

Autoimmune side effects were more common with ipilimumab than placebo
These could include skin reactions, gastrointestinal issues, and other autoimmune problems
Some early studies suggested autoimmune side effects may correlate with better treatment responses
Managing these side effects is an important part of using checkpoint inhibitors

Conclusion

This journal club episode provided in-depth discussion of two important papers - one on light exposure and mental health, and another on checkpoint inhibitor immunotherapy for cancer. Key takeaways include the powerful effects of properly timed light exposure on mental health, and the promise of harnessing the immune system to fight cancer, despite current limitations. The discussion also demonstrated how to critically analyze scientific papers and put findings into broader context. Overall, the episode highlighted exciting developments in circadian biology, mental health treatment, and cancer immunotherapy that could lead to improved health outcomes.