AMA #18: Cold Therapy Advice, Skin Health Tips, Motivation, Learning Strategies & More

KEYPOINTS

• 01

  Thinning skin with age reflects weakened collagen and elastin plus moisture loss

  Answering a 77-year-old listener, Huberman says excess sun categorically ages skin faster. You don't need to burn to raise your skin cancer risk, yet some sun is still needed for vitamin D, circadian rhythm and hormones; just avoid peak UV hours. His tiers run from zero-cost (sun protection, moisturizer) to moderate (collagen, red light) to prescription and procedures.

• 02

  Mineral sunscreens are the least controversial choice

  Physical barriers (hat, long sleeves) are undisputed but leave the ears, neck and parts of the face exposed. Zinc oxide and/or titanium dioxide up to about 25% are widely considered safe; if titanium dioxide worries you, use pure zinc oxide, at the cost of a pastier feel. Chemical filters like oxybenzone can reach the bloodstream with heavy use and may be endocrine disruptors. Huberman's stance: occasional use beats no protection, but for frequent all-summer use, choose mineral.

• 03

  Ingesting collagen has moderate evidence for skin elasticity

  Studies use 5–30 g a day (most often 15–30 g), often with vitamin C to aid absorption or utilization, and report statistically significant but not dramatic gains in elasticity, smoothness and plumpness. Sources include bone broth and fish or animal powders; plant-based versions are less clear.

• 04

  Red and near-infrared light panels also show moderate benefits

  Protocols run about 10–15 minutes a day, at least 5 days a week for a few months. Combining light with collagen might be synergistic, but that hasn't been tested. Retinoids, a dermatologist-supervised prescription option that increases sun sensitivity, are among the best-supported ways to improve collagen.

• 05

  Cold should be uncomfortable enough to make you want out, yet safe to stay in

  No systematic study defines the ideal time and temperature. Huberman works in 'walls': getting in, then rapid breathing, with clear thinking returning after about 20 seconds when hands and feet start to hurt. He suggests 1–3 minutes for most people, or 30 seconds if mental resistance is high. A gauge: put your hand in and rate your eagerness from 1 to 10; a 5 or 6 is about right. Novices might start around 55–60°F; he typically uses 45–50°F.

• 06

  Never do breathwork before getting into cold water

  Hyperventilating blows off CO2 and blunts the gasp reflex. People who did cyclic hyperventilation before going into water have blacked out and died. Ideally have someone watching who isn't in the water. Calm breathing while in is fine, but don't emphasize exhales and never deliberately submerge.

• 07

  Cold after lifting may blunt gains in some settings, but don't be paranoid

  Huberman says cold immersion right after resistance training can limit some strength and hypertrophy adaptations, but there is 'zero evidence' a cold shower after lifting does. His overall advice is to be neither too paranoid nor too obsessive about cold.

• 08

  REM sleep supports learning and strips emotional load from memories

  REM is concentrated toward morning, has more vivid, emotional dreams, and occurs with adrenaline essentially unavailable and the body paralyzed (atonia), making it a form of nightly trauma therapy. The first night after learning something matters most. Alcohol and late caffeine disrupt REM, and no drug clearly and specifically increases it.

• 09

  Brief pauses during learning trigger 20–30x speed replay

  Papers on music, math, concept and motor learning show that random ~10-second 'micro gaps' let the hippocampus and neocortex replay the material (sometimes in reverse) at 20–30 times normal speed, adding repetitions for free. This mirrors replay during REM sleep. Huberman suggests one to five, or even up to 10, gaps per hour, without phones or reviewing the material during them.

• 10

  Shilajit sits low on Huberman's testosterone list

  Shilajit is a Himalayan mineral pitch with many fakes. Studies summarized on Examine include one with 60 participants showing a small testosterone increase, small FSH increases and a slight sperm-quality gain. Because it may raise FSH, he cautions it could disrupt menstrual cycles. Fixing body fat (neither too high nor too low), sleep and training does far more; he says even a 20-minute increase in REM sleep would beat shilajit for testosterone.