Psychedelic microdosing is a practice to use sub-threshold doses of psychedelic drugs in an attempt to improve creativity, boost physical energy level, emotional balance, increase performance on problems-solving tasks and to treat anxiety, depression and addiction. 
In 2018, a group of scientists at Imperial College London announced a self-blinding study recruiting volunteers across the globe via Internet, using questionnaires and games to evaluate psychological well-being and cognitive function effects of psychedelic microdosing.
A study published in 2019 tested the microdosing hypothesis by subjecting male and female Sprague Dawley rats to behavioral testing following the chronic, intermittent administration of low doses of the psychedelic N,N-dimethyltryptamine (DMT). The behavioral and cellular effects of this dosing regimen were distinct from those induced following a single high dose of the drug. The study found that chronic, intermittent, low doses of DMT produced an antidepressant-like phenotype and enhanced fear extinction learning without impacting working memory or social interaction. Additionally, male rats treated with DMT on this schedule gained a significant amount of body weight during the course of the study. Taken together, results suggest that psychedelic microdosing may alleviate symptoms of mood and anxiety disorders, though the potential hazards of this practice warrant further investigation.