Mood is not simply an emotional state, such as sadness or joy. It determines more broadly the beliefs we generate about the world, emotional reactions, and what drives us to seek rewards or flee from dangers. From an evolutionary point of view, mood could thus be a regulator of our behavior, allowing us to adapt to changes in our environment.", indicated Hugo Bottemanne, psychiatrist at the Paris Brain Institute, in April 2024. He was then analyzing the influence of weather on mood.
But how does it change over time? A new observational study from University College London looked at seasonal, weekly, and daily fluctuations in mood. Using a detailed questionnaire, the researchers identified periods that are more conducive to well-being, particularly in the morning. Their results were published in the journal BMJ Mental Health.
Summer, associated with an abundance of food resources
In their publication, the researchers analyzed data from a social study that began in March 2020, during the coronavirus pandemic. Different aspects of mood were measured using questions. For example: "aOver the past week, how happy have you felt? or even, “How satisfied have you been with your life?”. More than 49,200 people responded to these regular surveys. The result? The study initially confirms the influence of the season on mood.
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"The mental health of the participants was definitely better during the summer period," report the scientists. Depressive and anxiety symptoms were less frequent, as was loneliness. Satisfaction and happiness had increased. The study is observational and therefore cannot establish causal links. However, several studies indicate that the number of hours of sunlight plays an important role in this change in state of mind.
"Temperature, precipitation or humidity could also be factors in mood variability," suggest the authors. Indeed, there is a lot of research on the effect of weather conditions on mental health. Over the course of its evolution, the human brain would have gradually associated the weather with the potential for food rewards. Sunny summer periods are conducive to the abundance of resources: fruit ripening, plant growth, animal reproduction, etc.
Conversely, winter periods are associated with a decrease in resources. So, our brain would have to interpret these weather variables as an indication of the probability of encountering food resources“, summarized Hugo Bottemanne. “ Evolution would thus have favored a regulation of our exploration behaviors (when mood is high) and reserve behaviors (when mood is low) according to these meteorological signals.”
An optimum at 8 a.m.
In this new study, researchers tried to identify mood variations within a day. “Mental health and well-being are dynamic factors by nature and likely to change over more or less long periods of time,” note the researchers. They therefore analyzed several factors according to the time of day: mental health (depressive and/or anxiety symptoms), happiness, life satisfaction, the feeling of having a life worth living and social well-being. Their work reveals a clear trend: in the morning, mood is generally better, all factors are evaluated more positively, particularly around eight o'clock. As for the most critical time, it is midnight!
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The researchers suggest that such variations could be explained by physiological changes associated with our biological clock.For example, cortisol levels peak shortly after waking up and are lowest around bedtime. But it's also important to recognize the differences between weekends and weekdays," they write. Indeed, there are also less marked weekly trends.
Happiness, life satisfaction, and life worth were all higher on Mondays and Fridays than on Sundays, and happiness was also higher on Tuesdays. "Given that there is little evidence that physiological processes differ across days of the week, the differences could be related to contextual factors and the sequence of daily activities," the authors advance.
Finally, mental health and well-being tend to be at their lowest around midnight, midweek, and in winter. Researchers say these findings could provide a better understanding of clinical assessments.
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