Which are the drugs which are normally used as medicines to help patients cope up with mental illness like depression and insomnia and are often abused?

Drugs like barbiturates, amphetamines, benzodiazepines, lysergic acid diethyl amides ($LSD$) and other similar drugs are normally used as medicines to help patients cope with mental illness. From the ergot of mustard seed, lysergic acid is formed, from that $LSD$ is produced.

Amphetamines are stimulating pills. People who keep awake at night, use Amphetamines, its effect resemble cocaine.

Barbiturates are a medicine which makes a person feels comfort and relief, they are also known as sleeping pills.

Morphine is a very effective sedative and painkiller and is useful in patients who have undergone surgery.