About Workplace Mental Health
The seasonal pattern is real
GP consultations for depression and anxiety follow a seasonal curve. Referrals to psychological services tend to peak in autumn and winter. Mood disorders with a clear seasonal component, classified as Seasonal Affective Disorder, or SAD, affect around one in fifteen people in the UK, with many more experiencing milder but still significant shifts in energy, mood, and motivation across the year.
The popular explanation is sunshine. The weather gets better, we feel better. That is intuitively satisfying. It is also probably incomplete.
If it were the temperature, hot countries would have better mental health
This is where the assumption runs into difficulty. Countries with sustained high temperatures, parts of the Middle East, South Asia, sub-Saharan Africa, do not consistently show lower rates of depression or anxiety. Some show higher rates. The Gulf states, where temperatures are extreme for months and outdoor life retreats indoors for much of the year, do not report universally positive mental health outcomes despite continuous warmth.
Conversely, the Scandinavian countries, Finland, Sweden, Denmark, Norway, experience long, dark, cold winters, and yet they regularly rank among the highest in the world for wellbeing and life satisfaction. Something other than temperature is driving these patterns.
If sunshine were the answer, Saudi Arabia would have the world’s best mental health data. It does not.
Light is not the same as warmth
The strongest biological mechanism linking season to mental health is not temperature, it is light. Specifically, natural daylight affects the regulation of melatonin, the hormone that governs sleep-wake cycles, and is associated with serotonin activity in the brain. Disruption to these systems, through insufficient daylight exposure during waking hours, is the most well-supported explanation for Seasonal Affective Disorder.
This is why light therapy, exposure to a specific intensity of artificial light in the morning, is an effective treatment for SAD in clinical settings. It is not replicating summer. It is replicating sufficient light. The two are related but not identical.
What changes in summer is behaviour, not just weather
When summer arrives in the UK, several things change simultaneously. People spend more time outside. They exercise more. They socialise more, in gardens, parks, and public spaces. They maintain more regular sleep patterns because of natural light cues. They feel more agency over their time and environment.
These behavioural changes, increased physical activity, more social connection, more time in natural environments, more exposure to daylight, are all independently associated with better mental health outcomes. Summer weather does not improve mental health directly. It creates conditions in which people are more likely to do the things that improve mental health.
That distinction matters for employers. Because some of those conditions can be created regardless of the season.
The role of social connection
The Nordic countries have strong cultures of social infrastructure, trust in institutions, low inequality, and community connection. These factors, not climate, are generally understood to explain the apparent paradox of high wellbeing in cold, dark places. The absence of prolonged outdoor seasons has led to the development of compensating structures: indoor social culture, saunas as communal rather than private spaces, light festivals, strong community ties.
Meanwhile, extreme heat in other regions can be socially isolating. It drives people indoors, restricts movement, limits outdoor social activity, and in some cultural contexts reduces women’s mobility and social participation. The loneliness and loss of autonomy that can accompany sustained heat may partly explain why continuous warmth does not produce continuous wellbeing.
What this means for employers
The seasonal pattern in mental health is relevant for organisations because it affects workforce performance, absence, and wellbeing in predictable ways. Recognising this and responding to it practically is more useful than noting it and doing nothing.
Practical responses include ensuring access to natural light in the workplace, particularly in winter. They include flexible start times that allow employees to travel in daylight. They include policies that actively support physical activity rather than just encouraging it. They include attention to social isolation, particularly among remote workers or those in roles with limited team contact.
None of this requires waiting for good weather. It requires understanding what good weather actually gives people, and then asking whether your organisation can provide any of that independently.
The honest conclusion
Summer probably does improve how many people feel. But the mechanism is more about what summer enables than what summer is. It enables more light, more movement, more connection, more time outdoors. These are not luxuries. They are the conditions under which human beings, including your employees, tend to function best. The question is how seriously you take that outside of July and August.
About Peter Kelly and Being Real
Peter J Kelly is an occupational psychologist with more than 20 years at the Health and Safety Executive shaping national policy on workplace mental health. He was a member of the ISO 45003 drafting panel, the world’s first international standard for psychological health and safety at work. Being Real is his specialist consultancy, helping organisations move from policy to practice.
If you would like to talk about what real support looks like in your organisation, contact Peter at being-real.co.uk