This is what some refer to as Blue Monday.
A UK travel company first claimed that the third Monday in January was the most depressing day of the year as part of a 2005 marketing campaign.
Sky Travel backed the idea with an arbitrary equation based on factors including winter weather, post-holiday letdown, and bills.
While there is no scientific proof behind Blue Monday, many people in the Northern Hemisphere do struggle with seasonal affective disorder (SAD), a type of depression, at this time of year.
Experts often recommend sunlight, sleep, exercise and other healthy lifestyle choices to boost mood during the dark and cold winter months.