Μake us preferred on Google As temperatures rise, nights become harder to endure and sleep is disrupted, while everyday life becomes more demanding. For most people, the effects of a heatwave are limited to fatigue, discomfort and irritability. But for people living with serious mental health disorders, prolonged heat can add another burden.
The relationship between weather, seasonality and mental health has increasingly come under scientific scrutiny in recent years. A Greek study examining thousands of involuntary psychiatric admissions in Attica — admissions made without a patient’s consent — adds important evidence to that discussion.
Athanasios Douzenis, professor of Psychiatry and Forensic Psychiatry at the National and Kapodistrian University of Athens, said high temperatures and heatwaves can affect mental health, particularly among people who already have serious psychiatric disorders.
That does not mean, he stressed, that a particular patient will relapse simply because summer has arrived. Rather, the data point to increased vulnerability at the population level, which becomes visible when large numbers of patients are examined.
An eight-year study in Attica
The study, titled “The Impact of Meteorological Factors on Involuntary Admission in Attica, Greece,” was led by Ioannis Rizavas, an NKUA doctoral researcher and mental health nurse.
Conducted at the Daphni Psychiatric Hospital in Attica, the study covered eight consecutive years, from 2010 through 2017. Researchers examined 6,887 cases of involuntary psychiatric hospitalization and combined the records with daily meteorological data from the National Observatory of Athens.
The researchers did not look only at temperatures. Their analysis included several meteorological variables and examined whether particular combinations of weather conditions were associated with changes in the daily number of involuntary admissions.
The findings showed a clear seasonal pattern.
The highest proportion of involuntary admissions was estimated around mid-June, at approximately 6.5% above the average, while the lowest occurred around mid-December, at about 6.1% below the average.
The long-term trend also corresponded to an increase of about 4% in admissions per year, a pattern that reflects the increasing frequency and duration of heatwaves.
Among the weather variables associated with changes in the average daily number of involuntary admissions were maximum temperature, wind speed and atmospheric pressure.
The finding suggests that the relationship between weather and mental health is more complicated than a simple equation in which higher temperatures automatically mean more hospitalizations.
Serious mental disorders and psychosis
Douzenis focuses particularly on major mental disorders and psychotic disorders. Seasonality appears particularly pronounced in mood disorders, he said, but is also observed in other psychotic disorders, including schizophrenia.
The crucial point, however, is not to interpret population-level statistics as a certainty for an individual patient.
For example, a person with bipolar disorder or schizophrenia who is stable, follows their treatment and remains under medical supervision will not necessarily relapse because temperatures rise.
As Douzenis explained, a person living with a chronic mental illness may experience an exacerbation at some point, but it is impossible to predict exactly when that will happen. What the data show is that, across large populations, the probability of an exacerbation is higher during certain warm periods and under particular meteorological conditions.
The seasonal pattern is not unique to Greece. A systematic review by the same research group examined 31 international studies on hospitalizations among people with serious mental disorders. The findings provided strong evidence of peaks in relevant admissions during the spring and summer, although the researchers noted that data specifically concerning involuntary hospitalizations remain more limited.
Insomnia can be an early warning sign
Among the symptoms that deserve particular attention, Douzenis highlights insomnia.
Sleep disruption is common during summer. A hot night can keep even a healthy person awake. But for someone living with a chronic mental illness, a sudden and persistent change in sleep can be an early warning sign that something is beginning to change.
“The appearance of insomnia shows that something is beginning to go wrong,” the professor said, referring specifically to people with chronic mental illness.
At the same time, he stressed that the surrounding circumstances must be considered. If someone cannot sleep simply because their room is excessively hot, the cause may be different, even though the resulting lack of sleep can still place additional strain on them.
What matters, therefore, is whether a change in sleep is accompanied by other changes in the person’s usual behavior.
In addition to insomnia, warning signs can include reduced energy, withdrawal from activities, a tendency to become more isolated, unusually intense irritability and heightened sensitivity. Some mood disorders may also involve a loss of appetite.
Douzenis also identifies sudden increases in alcohol or other substance use, as well as increased smoking, as signs that deserve attention. Someone who previously drank only occasionally but suddenly begins consuming significantly more alcohol every day, for example, may be experiencing increased anxiety and internal tension.
None of these signs, on its own, proves that a person is relapsing. But when several appear together, or when they represent a clear behavioral change in someone with a known psychiatric history, they should prompt greater vigilance and communication with the treating clinician.
Greater pressure on psychiatric services
The effects extend beyond patients and their families and can also place additional pressure on the health care system.
Douzenis said clinical experience shows periods with more relapses and a greater need for hospital admissions. The increased pressure on psychiatric beds was also reflected statistically in the study.
That finding takes on added significance amid the climate crisis. If extreme heat events become more frequent or last longer, mental health services may need to incorporate weather into their planning — not as the sole factor determining demand, but as another variable that can affect the need for care.
The researchers similarly point to the increasing frequency of extreme weather events as a reason to adapt how mental health services are organized.
Awareness, not fear
Douzenis emphasizes that greater awareness should not turn into fear.
A person with a psychiatric history does not need to view summer as a period when something inevitably “will happen.” Excessive anxiety can itself become an additional burden.
Instead, he recommends maintaining good communication with a psychiatrist or therapist, remaining consistent with treatment, staying adequately hydrated, avoiding excessive exposure to the sun and very high temperatures, and paying attention to unusual changes in sleep or behavior.
Particular care is also needed regarding psychiatric medications during very hot weather. Any concerns about medication should be discussed with the treating clinician, and patients should not make changes to their treatment on their own.
