There are some matters that harm the mind...

Four Matters Harm the Mind & the Intellect



Eating sour foods and fruits excessively

Sleeping on the back
Depression
Sadness


Four Matters Strengthen the Mind & Intellect


When the heart is not busy (or concerned)
Consuming moderate amounts of food and drink
Dieting on good combinations of sweets and nutritious foods
Getting rid of harmful substances in the body


There are some matters that harm the mind:

eating onions, beans, olives and eggplant excessively
having too much sexual intercourse
loneliness
worrying
intoxication
excessive laughing
depression


Source:


Healing with the Medicine of the Prophet (sallallaahu 'alaihi wa sallam)
Ibn al Qayyim al Jawziyyah (rahimahullaah)
Pages 356 - 357