SB 12.3.30
yada mayanrtam tandra
nidra himsa visadanam
soka-mohau bhayam dainyam
sa kalis tamasah smrtah
Translation:
When there is a predominance of cheating, lying, sloth, sleepiness, violence, depression, lamentation, bewilderment, fear and poverty, that age is Kali, the age of the mode of ignorance.
Purport:
In Kali-yuga, people are almost exclusively devoted to gross materialism, with hardly any affinity for self-realization.