The experience of feeling suddenly cold or beginning to shiver during an altered state is a common physiological reaction, often referred to as “weed shakes.” This temporary side effect occurs after consuming psychoactive substances, particularly cannabis. The body’s response results from the substance interacting with the brain’s regulatory systems, which mistakenly signal a drop in temperature. Understanding the science behind this reaction can help demystify the feeling.
How the Body Regulates Temperature
The human body maintains a stable internal temperature through a process called thermoregulation. The central command center for this process is the hypothalamus, a small region in the brain that acts like a sophisticated thermostat. This internal thermostat constantly monitors the core body temperature and signals received from skin receptors.
When the hypothalamus detects a core temperature that is too low, it triggers automatic responses to generate and conserve heat. The most noticeable response is shivering, which involves rapid, involuntary contractions of the skeletal muscles. These movements expend energy and release heat as a byproduct, raising the body’s internal temperature back to the set point.
The body also initiates heat-conserving mechanisms, such as vasoconstriction, where blood vessels near the skin surface narrow. This action reduces blood flow to the extremities, limiting heat loss and keeping warmer blood concentrated around vital internal organs.
The Neurochemical Cause of the Cold Sensation
The cold sensation and subsequent shivering result from a neurochemical interaction involving tetrahydrocannabinol (THC). THC is the main psychoactive component in cannabis, and it achieves this by binding to specific receptors in the brain and body. These receptors are part of the endocannabinoid system, which naturally regulates mood, memory, appetite, and temperature.
THC specifically targets Cannabinoid Receptor Type 1 (CB1) receptors, which are densely located in the hypothalamus. When THC activates these receptors, it temporarily interferes with the hypothalamus’s ability to maintain its normal temperature set point. This interference causes the internal thermostat to be lowered, or “down-shifted,” by a small amount.
Since the body’s actual core temperature has not changed, it now registers as too high relative to this new, lower set point. This neurological miscommunication tricks the hypothalamus into thinking the body is dangerously cold. The brain then immediately activates heat-generating mechanisms, such as involuntary muscle contractions, resulting in shivering to reach the artificially low temperature threshold.
When Shivering Indicates a Problem
While the shivering caused by a temporary shift in the brain’s temperature set point is usually harmless, it is important to differentiate this reaction from signs of a more serious issue. Benign shivering typically occurs shortly after consumption, is often accompanied by the expected psychological effects, and subsides as the substance’s intensity wanes. However, shaking or tremors can also be a physical manifestation of high anxiety or a panic attack, which can be triggered by high doses of the psychoactive compound.
If the shaking is accompanied by severe symptoms, it could signal a reaction that requires medical attention. Signs like extreme confusion, the inability to speak coherently, chest pain, or a sustained, rapid heart rate that does not slow down are reasons for concern. Additionally, if the shaking is severe enough to interfere with basic motor function or if it escalates into a sustained high fever or loss of consciousness, professional medical help should be sought immediately. These severe reactions are rare, but recognizing the difference between a temporary side effect and a genuine adverse event is important for safety.
Immediate Steps to Cope with the Cold
If you begin to feel cold or experience involuntary tremors, there are several immediate, practical steps you can take to manage the temporary discomfort. Focusing on mental techniques can also be helpful, as panic can worsen the physical symptoms. Taking slow, deep breaths and repeating a simple reassurance that the feeling is temporary and physiological can help calm the nervous system until the effect passes.
Other steps include:
- Physically warming the body by wrapping yourself in a blanket or moving to a warmer environment.
- Consuming a warm beverage, such as herbal tea or water, can help raise the internal temperature slightly and provide a sense of comfort.
- Eating a light snack containing carbohydrates, since low blood sugar can sometimes contribute to general shakiness.