Marijuana has been a popular drug long before it was legalized across several states in the US. This plant shows up in the archeological records 37 million years ago, and humans have been using this plant for various purposes 8,000 years ago. Besides medicinal uses, people have also found value in the plants' seeds for nutrition and stems for durable fibers.
But today, marijuana is mostly known for its psychoactive effects. This property is due to the chemical tetrahydrocannabinol or THC. THC works by mimicking the natural cannabinoids in the body to stimulate thinking, memory, pleasure, and spatial perception. Specifically, THC acts like the neurotransmitter called anandamide, which regulates hunger, sleeping, and pain relief. This is why users experience these proverbial symptoms upon marijuana exposure.
In studies attempting to find a toxic limit for THC consumption, researchers gave rats a dose 40,000 times higher than normal. This had the effect of making them sleep for 3 days. Marijuana dependency is lowest even when compared to common addictive substances like caffeine or alcohol.
Aside from its recreational feel-good effects, researchers have found uses for marijuana in medicine, as the plant can relieve vomiting and pain for chemotherapy patients, reduce epilepsy episodes, and treat insomnia. This is due to marijuana containing at least 85 other cannabinoids besides THC, each with different effects on the body. As such, farmers have bred countless strains of the plant, with each strain capitalizing on certain chemical properties. And most of the strains intended for medical purposes have had the THC selectively bred out.