Summary
The Huberman Lab Podcast episode delves into the biology of thermal regulation and the benefits of saunas and other heat-related tools for health and optimization. The body has neurons that send signals to other cells to heat up or cool down depending on the temperature of the environment. It's important to understand the effects of the heating and cooling process on the shell and core. The circuit for heating up involves neurons in the skin, dorsal horn of the spinal cord, lateral parabrachial area, and preoptic area (POA). The POA sends signals out to the organs and tissues of the body, causing them to dilate blood vessels, sweat, and stop shivering. The use of deliberate heat exposure, such as saunas, has been found to improve health and longevity by reducing mortality from cardiovascular events and stroke.
To obtain optimal results, sauna temperature should range between 80 and 100 degrees Celsius, and each session should last between five and 20 minutes. Deliberate heat exposure can lead to hormone effects, such as reductions in cortisol and increases in growth hormone. The mechanism behind these effects involves activation of neurons in the preoptic area and changes in the autonomic nervous system, leading to increases in heart rate and blood volume. A study on men found that repeated exposure to hot thermal stress and cold water immersion can significantly decrease cortisol output.
The episode also discusses the benefits of sauna exposure on reducing cortisol levels, activating heat shock proteins, and increasing FOXO3 and growth hormone. Sauna exposure has been shown to decrease cortisol levels, which can help reduce stress. Heat shock proteins are protective mechanisms that rescue proteins that would otherwise misfold, and deliberate heat exposure can activate these proteins. FOXO3 is a molecule that is involved in DNA repair pathways and clearing out senescent cells, and sauna exposure can upregulate its levels. Growth hormone is a hormone that impacts metabolism and growth, and sauna exposure can increase its secretion.
The podcast episode highlights the use of heat and cold exposure to stimulate heat shock proteins, growth hormone, and other benefits. It is important to find what works best for each individual and to consult with a doctor before starting. The recommended parameters for heat exposure are between 80-100 degrees Celsius for 5-20 minutes, but longer exposure can be done for more intense results. The timing of heat exposure is important, and it is recommended to do it later in the day for optimal results. Cold exposure can be done earlier in the day to match the natural heating of the body. To promote growth hormone release, it is recommended to do sauna fasted or at least not having ingested any food in the two or three hours before.
Moreover, the podcast episode explains the benefits of deliberate heat exposure on both physical and mental health. Sauna exposure can aid in the transition to sleep and improve mood and mental health by upregulating pathways that allow for the experience of pleasure. It also activates the dynorphin system, which can increase the efficiency of feel-good endorphins in the brain and body. Studies have shown that frequent sauna use is associated with a decreased risk of psychotic disorders. It is important to hydrate after sauna use to replace lost water and electrolytes.
Lastly, the podcast episode touches on the exciting new science around local heating, which can change the identity of certain fat cells and increase the conversion of white fat to beige fat. A recent study has found that local heat therapy can convert white fat to beige fat, which is metabolically active and can lead to increases in metabolism and improvements in glucose metabolism and thermogenesis. The study involved heating the skin up locally in certain locations on the body, such as the upper back and neck, using a thermocouple, and resulted in the increase of a promoter that regulates the activity of genes involved in glucose and
