Generally, things really do seem better in the morning, with clear patterns across time of day in how we report our mental health and wellbeing, suggest the findings of a large study led by researchers at UCL.
The findings, published in the open access journal BMJ Mental Health, suggest that people generally wake up feeling in the best frame of mind in the morning but in the worst around midnight, with day of the week and season also playing their part. But the researchers caution that the findings need to be replicated in other studies to be sure they are a true picture.
Relatively few studies have looked at how mental health and wellbeing might change over the course of the day, and those that have tended to use small and selective samples, the researchers said.
The team therefore wanted to explore whether time of day was associated with variations in mental health (depressive and/or anxiety symptoms), happiness (hedonic wellbeing), life satisfaction, sense of life being worthwhile (eudemonic wellbeing) and loneliness (social wellbeing). They also wanted to find out if these associations varied by day, season, and year.
Lead author Dr Feifei Bu, from UCL's Department of Behavioural Science & Health, said: "Our findings suggest that on average, people's mental health and wellbeing are better in the morning and worst at midnight. We drew on a large sample of repeated data - nearly a million survey responses from 49,000 participants over two years.
"However, this pattern could reflect when people choose to respond to the survey, rather than a direct effect of time of day. For example, those already feeling better in the morning might be more likely to engage with the survey at that time.
"While these findings are intriguing, they need to be replicated in other studies that fully account for this potential bias. If validated, this could have important practical implications. Researchers investigating people's mental health and wellbeing should take into account the time of day people respond. Mental health support services might consider adjusting resources to match fluctuating needs across the day-for instance, prioritising late-night availability."
The team analysed longitudinal data from the UCL COVID-19 Social Study, which began in March 2020, and involved regular monitoring until November 2021, and then additional monitoring up to March 2022.
All aspects of mental health and wellbeing were measured via online questionnaires using validated assessment tools or through single direct questions: "In the past week, how happy did you feel; how satisfied have you been with your life; to what extent have you felt the things you are doing in your life are worthwhile?"
Time stamps on completion of each survey provided information on time of day (continuous from 6 am to midnight); day of the week; season; and year (2020, 2021, 2022).
Information on other potentially influential factors included age, gender, ethnicity, educational attainment, employment status, residential area (rural, urban) and diagnosed physical and mental health conditions.
Complete information was available for 49,218 people, three quarters of whom (76.5%) were women. People educated to degree level or above were over-represented (68%) while those from ethnic minority backgrounds were under-represented (6%). The sample was therefore weighted to reflect population proportions.
Analysis of the data revealed a clear pattern across time of day in self-reported mental health and wellbeing, with people generally waking up in the morning feeling best-lowest depressive/anxiety symptoms and loneliness and highest happiness, life satisfaction, and worthwhile ratings-and feeling worst around midnight.
The influence of day of the week was less clear-cut, with more variation in mental health and wellbeing during weekends than on week days.
Happiness, life satisfaction, and worthwhile ratings were all slightly higher on Mondays and Fridays than on Sundays, and happiness was also higher on Tuesdays. But there was no evidence that loneliness differed across days of the week.
There was clear evidence of a seasonal influence on mood. Compared with winter, people tended to have lower levels of depressive and anxiety symptoms and loneliness, and higher levels of happiness, life satisfaction, and feeling that life was worthwhile in other seasons. And mental health was best in the summer across all outcomes. The season didn't affect their associations with time of day, however.
Mental health and wellbeing also steadily improved from 2020, the first year of the COVID-19 pandemic, to 2022.
This is an observational study, and as such, cannot establish causality. No information was available for sleep cycles, latitude, or weather, all of which may also have been influential, the researchers said.
But the changes in mental health and wellbeing across the day might be explained by the physiological changes associated with the body clock.
The researchers wrote: "For example, cortisol peaks shortly after waking and reaches its lowest levels around bedtime. However, it is important to acknowledge the differences between weekends and weekdays.
"Given there is little evidence that physiological processes differ across different days of the week, differences might be related to other factors that drive [mental health and wellbeing] changes over the course of the day. This could include contextual factors and sequence of daily activities, which are likely to be different between weekends and weekdays."
