The phenomenon of Blue Monday, or “sad Monday,” which in 2025 fell on January 20, has once again attracted attention. The history of this unofficial “saddest day of the year” dates back to 2005, when a British psychologist presented an interesting theory about the peak of the winter blues, writes "MIR 24" with reference to Forbes.

Cliff Arnold, a British psychologist, proposed a mathematical formula for determining the most depressive day: [W+(D-d)] x TQ/M x NA. This equation takes into account various factors: weather conditions (W), financial obligations (D), wages (d), time after the holidays (T), failure to keep New Year's resolutions (Q), level of motivation (M) and need to act (NA). According to calculations, it is the third Monday of January that becomes the point of intersection of all these negative factors.

However, the scientific community is skeptical about this theory. Experts warn that the very expectation of a “bad day” can turn into a self-fulfilling prophecy: people begin to notice only negative events, which can actually worsen their emotional state.

At the same time, January is objectively considered a difficult month for residents of the Northern Hemisphere. Short daylight hours, cold weather and limited time outdoors actually affect melatonin production, which affects a person's mood and energy levels. Experts recommend getting more sun exposure, eating a healthy diet, and maintaining a regular daily routine to maintain emotional balance during this period.