5-HTP (5-hydroxytryptophan) is a naturally occurring amino acid that is used as a dietary supplement to increase serotonin levels in the brain, potentially aiding in the treatment of conditions such as depression, anxiety, and ADHD. It can improve mood, suppress appetite, and promote sleep, but common side effects include gastrointestinal issues. ADHD is a developmental disorder linked to genetic factors and neurotransmitter imbalances, and while 5-HTP may help manage some symptoms of ADHD, it should be used cautiously and not in combination with other serotonin-affecting medications.