Blue Monday (date)

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Blue Monday is the name given to a day in January (typically the third Monday of the month) by former Cardiff University health psychologist [1] and Post-Graduate Medical and Dental tutor Cliff Arnall in 2005. [2] [3] [4] It is said by a UK travel company, Sky Travel, to be the most depressing day of the year. It takes into account weather conditions and thus only applies to the Northern Hemisphere.

Contents

Some have dismissed the idea as pseudoscience. [5] Others, including the Samaritans, have used Blue Monday to facilitate talk about mental health. [6]

Date

The date is generally reported as falling on the third Monday in January, [7] but also on the second or fourth Monday. [7] The first such date declared was 24 January in 2005 as part of a Sky Travel press release. [8]

Calculation

The formula uses six factors, including: weather conditions, debt level (the difference between debt accumulated and ability to pay), time since Christmas, time since New Year's resolutions have been broken, low motivational levels, and the feeling of a need to take action.

Blue Monday Formula: Empirical Evidence and Scientific Basis

The Blue Monday formula is a psychosocial framework developed by Cardiff University psychologist Cliff Arnall in 2005 [9] [10] to identify and explain a confluence of factors contributing to low mood and psychological distress typically observed in mid-to-late January. While originally presented as a mathematical formula, [8] the concept has evolved into an evidence-based heuristic model supported by peer-reviewed research across multiple disciplines including clinical psychology, chronobiology, behavioural economics, and public health.

Formula Structure

The Blue Monday formula is expressed as:

Where:


Empirical Evidence for Core Factors

Weather, Light Exposure, and Seasonality (W)

The influence of reduced light exposure on seasonal mood disruption is well established in clinical literature. A 2025 meta-analysis by Wan et al. (2025) [11] demonstrated that white-light phototherapy produced superior clinical effects in reducing Seasonal Affective Disorder (SAD) symptoms compared to other wavelengths, establishing a direct therapeutic link between light exposure and symptom relief.

Raza et al. (2024) [12] conducted a within-individual analysis observing small-to-medium associations between higher daytime light exposure in winter and lower probability of depressive symptoms across various populations. A clinical review by Munir (2024) [13] provides additional support, detailing diagnostic criteria for SAD and confirming robust patient response to light therapy treatments.

Financial Debt and Payment Capacity (D-d)

Research consistently demonstrates a bidirectional relationship between unsecured debt and mental health outcomes. Bhugra and Ventriglio (2024) [14] conducted a narrative review emphasizing that debt significantly increases risk for stress-related outcomes, anxiety, and depression.

The Money and Mental Health Policy Institute (2024) [15] reported a spike in debt advice-seeking service utilization specifically in January in the United Kingdom, reinforcing the temporal relationship between post-Christmas financial difficulties and mental health declines. Foundational longitudinal research by Sweet et al. (2013) [16] involving 8,400 US adults demonstrated that unsecured debt is associated with increased depressive symptoms independent of income, with regression analyses showing higher odds of depression corresponding to rising debt levels.

Post-Holiday Timing (T)

Research indicates a rebound effect wherein mood declines following the conclusion of holiday festivities. Schneider et al. (2023) [17] conducted a systematic review and single-centre analysis finding that while psychiatric hospitalizations decreased during the Christmas period, evidence supported a rebound in dysphoria and psychiatric presentations after the holidays. This pattern was previously documented by Sansone and Sansone (2011), [18] who identified a post-holiday "letdown" following decreased emergency psychiatric utilization around Christmas.

Failed New Year's Resolutions (Q)

Empirical data consistently show high attrition rates for New Year's resolutions. Norcross and Vangarelli (1988) [19] tracked 200 resolution-makers and found that only 77% maintained their resolution for a single week, with rapid early failure rates. The psychological impact of failed resolutions contributes to feelings of inadequacy and low mood during the January period.

Motivational Levels and Energy (M)

Reduced energy and motivation are linked to seasonal and circadian disruption. Dollish et al. (2023) [20] provided mechanistic evidence demonstrating that chronobiological disruptions -including reduced daylight and evening chronotypes - increase risk for depressive symptoms and low motivation, directly linking winter circadian changes to reduced motivational capacity.

A systematic review by Rizavas et al. (2023) [21] confirmed that seasonal effects act as a risk factor that can exacerbate symptoms and reduce motivation in vulnerable individuals.

Need to Take Action and Intention-Action Gap (NA)

The perceived gap between intended behavioural change and actual behaviour creates psychological discomfort. Experimental work by Elliot and Devine (1994) [22] demonstrated that cognitive dissonance - the discrepancy between one's goals and current behaviour - causes negative affect and motivates corrective action, which can amplify negative psychological symptoms.

Gollwitzer and Sheeran (2006) [23] conducted a meta-analysis finding that forming concrete implementation intentions ("if X, then I will do Y") significantly increases goal attainment compared to setting goals alone, suggesting practical interventions to address this factor.

Academic Assessment and Practical Utility

The convergence of six distinct, empirically supported psychosocial and biological factors provides a heuristic framework for understanding population-level mood variations observed in early-to-mid January. The Blue Monday concept functions not as a deterministic equation but as a practical risk model that allows for targeted, evidence-based intervention.

Core components include the biological impact of reduced winter light and circadian disruption (W, M), which contributes to low motivation and SAD symptoms. The model highlights immediate psychosocial stressors including post-holiday unsecured debt (D-d) - robustly linked to increased depressive and anxiety outcomes - and the failure of New Year's resolutions (Q), a widely documented phenomenon. The timing is reinforced by the post-holiday letdown effect (T) and the psychological burden of the intention-action gap (NA), where perceived need to change causes distress.

Practical applications of this model include deploying light therapy interventions, establishing financial advice pathways, reframing goals using approach-oriented strategies, and structuring specific implementation intentions to bridge the motivation gap, thereby proactively addressing the confluence of risks before mental health declines occur.

The 2005 press release [8] and a 2009 press release:

where W = weather, D = debt, d = monthly salary, T = time since Christmas, Q = time since the failure of new year's resolutions, M = low motivational levels, and Na = the feeling of a need to take action. No units are defined; the lack of any explanation for what is meant by "weather" and "low motivational levels" means the dimensional homogeneity of the resulting formula cannot be assessed or verified, rendering it meaningless.

One relationship used by Arnall in 2006 was: [24]

where Tt = travel time; D = delays; C = time spent on cultural activities; R = time spent relaxing; ZZ = time spent sleeping; St = time spent in a state of stress; P = time spent packing; Pr = time spent in preparation. Again, units are not defined; as all the factors involve time, dimensional analysis of the "formula" shows that it violates the fundamental property of dimensional homogeneity and is thus meaningless.

Evidence

Is Monday the most demotivating, peak stress, low mood day of the week?

A) Biological / Physiological Stress Markers

B) Mood over the working week

Based on peer-reviewed affect-psychology studies and the so-called 'Blue Monday' effect there is moderate support for Monday being the best candidate for the 'worst' or most 'demotivating' day of the week. This is because people tend to report more negative mood, less pleasure, and a greater sense of being overwhelmed on Mondays. [32]

British science writer Ben Goldacre has observed that Arnall's equations "fail even to make mathematical sense on their own terms", pointing out that under the 2006 equation, packing for ten hours and preparing for 40 will always guarantee a good holiday, and that "you can have an infinitely good weekend by staying at home and cutting your travel time to zero". [24] Dean Burnett, a neuroscientist who has worked in the Psychology department of Cardiff University, described the work as "farcical" with "nonsensical measurements", in 2013. [33]

In 2016, Arnall claimed to have attempted to "overturn" his "theory" by visiting the Canary Islands; his claim was publicised by the Canary Islands Tourism Board. [34]

History

This date was published in a press release under the name of Cliff Arnall, who was at the time a Research Associate in Psychology with University Hospital Wales (UHW), Department of Obstetrics & Gynaecology [35] and psychology tutor and psychologist at the Centre for Lifelong Learning [36] , a Further Education centre attached to Cardiff University. The Guardian columnist Ben Goldacre reported that the press release was delivered substantially pre-written to a number of academics via public relations agency Porter Novelli, along with an offer of money to those who offered to put their names to it. [24] A statement later printed in The Guardian sought to distance leaders of Cardiff University from Arnall: "Cardiff University has asked us to point out that Cliff Arnall … was a former part-time tutor at the university but left in February." [37]

Variations of the story have been repeatedly reused by other companies in press releases, with 2014 seeing Blue Monday invoked by legal firms and retailers of bottled water and alcoholic drinks. [38] Some versions of the story purport to analyse trends in social media posts to calculate the date. [38]

In 2018, Arnall told a reporter at the Independent newspaper that it was "never his intention to make the day sound negative", but rather "to inspire people to take action and make bold life decisions". It was also reported that he was working with Virgin Atlantic and Virgin Holidays, having "made it his mission to challenge some of the negative news associated with January and to debunk the melancholic mind-set of 'Blue Monday'". [39]

Happiest day

Arnall also says, in a press release commissioned by Wall's ice cream, [40] that he has calculated the happiest day of the year – in 2005, 24 June, [41] in 2006, 23 June, [42] in 2008, 20 June [43] and in 2010, 18 June. [44] So far, this date has fallen close to Midsummer in the Northern Hemisphere (June 21 to 24).

References

  1. ↑ "Access Restricted: Try-to-keep-smiling-until-the-saddest-day-of-the-year - 3 January 2006". www.telegraph.co.uk. Retrieved 15 November 2025.
  2. ↑ Tinworth, Adam (22 January 2007). "The Most Depressing Day of the Year". One Man & His Blog. Retrieved 8 November 2025.
  3. ↑ "Blue Monday: turn the saddest day of the year into a brighter day - Intelligent Marketing". 12 January 2024. Retrieved 8 November 2025.
  4. ↑ Mirror.co.uk (16 January 2012). "Today is Blue Monday for depressed Brits". The Mirror. Retrieved 15 November 2025.
  5. ↑ Burnett, Dean (16 January 2012). "Blue Monday: a depressing day of pseudoscience and humiliation". The Guardian . London. Retrieved 20 January 2014.
  6. ↑ Lifewellbeing. "The Samaritans - Make 'Blue Monday 'Brew Monday' in 2025". www.lifewellbeing.co.uk. Retrieved 9 November 2025.
  7. 1 2 Burnett, Dean (19 January 2015). "Blue Monday: is it really the most depressing day of the year?". The Guardian . Retrieved 20 January 2015.
  8. 1 2 3 "Jan. 24 called worst day of the year". NBC News. 24 January 2005. Retrieved 13 March 2007.
  9. ↑ "Pre-war Britons 'were happier'". 1 September 2005. Retrieved 15 November 2025.
  10. ↑ "'I don't like Monday 24 January'". 19 January 2005. Retrieved 15 November 2025.
  11. ↑ Wan, Yujie; Ding, Jiali; Fan, Mengmeng; Huang, Hailiang (4 July 2025). "Effectiveness of visible light for seasonal affective disorder: A systematic review and network meta-analysis". Medicine. 104 (27) e43107. doi:10.1097/MD.0000000000043107. ISSN   1536-5964. PMC   12237333 . PMID   40629637.
  12. ↑ Raza, Auriba; Partonen, Timo; Hanson, Linda Magnusson; Asp, Magnus; Engström, Erik; Westerlund, Hugo; Halonen, Jaana I (1 January 2024). "Daylight during winters and symptoms of depression and sleep problems: A within-individual analysis". Environment International. 183 108413. Bibcode:2024EnInt.18308413R. doi:10.1016/j.envint.2023.108413. ISSN   0160-4120.
  13. ↑ Munir, Sadaf (2024). "'Seasonal affective disorder'". StatPearls Publishing. 2025 Jan.
  14. ↑ Bhugra, Dinesh; Ventriglio, Antonio (1 December 2024). "Debt and mental ill-health". International Journal of Social Psychiatry. 70 (8): 1358–1359. doi:10.1177/00207640241291636. ISSN   0020-7640. PMID   39474924.
  15. ↑ "Money and Mental Health - a charity founded by Martin Lewis". Money and Mental Health Policy Institute. Retrieved 8 November 2025.
  16. ↑ Sweet, Elizabeth; Nandi, Arijit; Adam, Emma K.; McDade, Thomas W. (1 August 2013). "The high price of debt: Household financial debt and its impact on mental and physical health". Social Science & Medicine. 91: 94–100. doi:10.1016/j.socscimed.2013.05.009. ISSN   0277-9536.
  17. ↑ Schneider, Else; Liwinski, Timur; Imfeld, Lukas; Lang, Undine E.; Brühl, Annette B. (11 January 2023). "Who is afraid of Christmas? The effect of Christmas and Easter holidays on psychiatric hospitalizations and emergencies—Systematic review and single center experience from 2012 to 2021". Frontiers in Psychiatry. 13 1049935. doi: 10.3389/fpsyt.2022.1049935 . ISSN   1664-0640. PMC   9874097 . PMID   36713912.
  18. ↑ Sansone, Randy (December 2011). "The Christmas effect on psychopathology". Innov Clin Neurosci. 8 (12): 10–13. PMC   3257984 . PMID   22247812.
  19. ↑ Norcross, John C.; Vangarelli, Dominic J. (1 January 1988). "The resolution solution: Longitudinal examination of New Year's change attempts". Journal of Substance Abuse. 1 (2): 127–134. doi:10.1016/S0899-3289(88)80016-6. ISSN   0899-3289. PMID   2980864.
  20. ↑ Dollish, Hannah K.; Tsyglakova, Mariya; McClung, Colleen A. (3 January 2024). "Circadian rhythms and mood disorders: Time to see the light". Neuron. 112 (1): 25–40. doi:10.1016/j.neuron.2023.09.023. ISSN   0896-6273. PMC   10842077 . PMID   37858331.
  21. ↑ Rizavas, Ioannis; Gournellis, Rossetos; Douzenis, Phoebe; Efstathiou, Vasiliki; Bali, Panagiota; Lagouvardos, Kostas; Douzenis, Athanasios (28 July 2023). "A Systematic Review on the Impact of Seasonality on Severe Mental Illness Admissions: Does Seasonal Variation Affect Coercion?". Healthcare. 11 (15): 2155. doi: 10.3390/healthcare11152155 . ISSN   2227-9032. PMC   10418389 . PMID   37570395.
  22. ↑ Elliot, Andrew J.; Devine, Patricia G. (September 1994). "On the motivational nature of cognitive dissonance: Dissonance as psychological discomfort" . Journal of Personality and Social Psychology. 67 (3): 382–394. doi:10.1037/0022-3514.67.3.382. ISSN   1939-1315.
  23. ↑ Gollwitzer, Peter M.; Sheeran, Paschal (1 January 2006), Implementation Intentions and Goal Achievement: A Meta-analysis of Effects and Processes, Advances in Experimental Social Psychology, vol. 38, Academic Press, pp. 69–119, doi:10.1016/s0065-2601(06)38002-1, ISBN   978-0-12-015238-4 , retrieved 8 November 2025
  24. 1 2 3 Goldacre, Ben (16 December 2006). "MS = media slut, but CW = corporate whore". The Guardian . London. Retrieved 21 January 2008.
  25. 1 2 Becker, Tarani Chandola, Benjamin. "Your Body Really Does Have a Case of the Mondays". Scientific American. Retrieved 15 November 2025.{{cite web}}: CS1 maint: multiple names: authors list (link)
  26. ↑ Chandola, Tarani; Ling, Wanying; Rouxel, Patrick (2025). "Are anxious Mondays associated with HPA-axis dysregulation? A longitudinal study of older adults in England". Journal of Affective Disorders. 389 119611. doi:10.1016/j.jad.2025.119611. PMID   40482685.
  27. ↑ Kong, The University of Hong. "'Anxious Monday' effect: Chronic stress hormone surge linked to start of week in older adults". medicalxpress.com. Retrieved 15 November 2025.
  28. ↑ Rouhi, Shima; Egorova-Brumley, Natalia; Jordan, Amy S. (2025). "Painful Mondays: Exploring Weekly Sleep Variations and Pain Perception in Healthy Women—An Experimental Study". European Journal of Pain. 29 (4) e70004. doi:10.1002/ejp.70004. ISSN   1090-3801. PMC   11884311 . PMID   40047431.
  29. ↑ Schlotz, Wolff; Hellhammer, Juliane; Schulz, Peter; Stone, Arthur A. (2004). "Perceived Work Overload and Chronic Worrying Predict Weekend–Weekday Differences in the Cortisol Awakening Response". Psychosomatic Medicine. 66 (2): 207–214. doi:10.1097/01.psy.0000116715.78238.56. ISSN   0033-3174. PMID   15039505.
  30. 1 2 Suk, Hye Won; Choi, Eunsoo; Na, Jinkyung; Choi, Jongan; Choi, Incheol (2021). "Within-person day-of-week effects on affective and evaluative/cognitive well-being among Koreans". Emotion. 21 (5): 1114–1118. doi:10.1037/emo0000930. ISSN   1931-1516. PMID   33289572.
  31. ↑ Fochmann, Martin; Hechtner, Frank; Kirchler, Erich; Mohr, Peter N. C. (1 January 2025). "When happy people make society unhappy: Emotions affect tax compliance behavior". Journal of Economic Behavior & Organization. 229 106854. doi:10.1016/j.jebo.2024.106854. ISSN   0167-2681.
  32. 1 2 Ellis, David A.; Wiseman, Richard; Jenkins, Rob (19 August 2015). Longo, Matthew (ed.). "Mental Representations of Weekdays". PLOS ONE. 10 (8) e0134555. Bibcode:2015PLoSO..1034555E. doi: 10.1371/journal.pone.0134555 . ISSN   1932-6203. PMC   4544878 . PMID   26288194.
  33. ↑ Burnett, Dean (21 January 2013). "Blue Monday: a depressing day of nonsense science (again)". The Guardian . London. Retrieved 20 January 2014.
  34. ↑ Cliff Arnall Beats "the Blue Monday" Blues in the Canary Islands Press Release Canary Islands Tourism Board 17 January 2016
  35. ↑ Dawson, Andrew; Cohen, David; Candelier, Claire; Jones, Gill; Sanders, Julia; Thompson, Andy; Arnall, Cliff; Coles, Edward (1 December 1999). "Domiciliary midwifery support in high-risk pregnancy incorporating telephonic fetal heart rate monitoring: a health technology randomized assessment". Journal of Telemedicine and Telecare. 5 (4): 220–230. doi:10.1258/1357633991933756. ISSN   1357-633X.
  36. ↑ Yumpu.com. "Quench - Cardiff University". yumpu.com. Retrieved 23 November 2025.
  37. ↑ Goldacre, Ben (18 November 2006). "How GxPxIxC = selling out to your corporate sponsor". The Guardian . London. Retrieved 20 January 2014.
  38. 1 2 "Snopes: Blues Druthers". Snopes. 14 January 2015. Retrieved 20 January 2015.
  39. ↑ Peat, Jack (5 January 2018). "Man who coined the term 'Blue Monday' apologises for making January more depressing". The Independent . Retrieved 17 January 2024.
  40. ↑ "It's the happiest day of the year, formula shows". CTV.ca. 23 June 2006. Archived from the original on 20 January 2011. Retrieved 13 July 2007.
  41. ↑ "Cheer up for year's happiest day". BBC. 24 June 2005. Retrieved 13 March 2007.
  42. ↑ "Smile, it's the happiest day of the year". China Daily. 23 June 2006. Retrieved 13 March 2007.
  43. ↑ Smith, Rebecca (20 June 2008). "Today is the happiest day of the year according to Cliff Arnall's maths formula". The Daily Telegraph. London. Archived from the original on 22 June 2008. Retrieved 20 June 2008.
  44. ↑ Grant, Alistair (18 June 2010). "Happiness is, today, claims maths equation". Irish Examiner. Cork. Retrieved 18 June 2010.
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