Are you anxious about Monday? A study reveals it can cause heart problems.

'Sunday blues,' 'Sunday blues'... the arrival of Monday and the start of the work week can be a source of anxiety on Sundays, especially in the afternoons.

But in addition to the symptoms of depression or anxiety that they can generate, this distress can cause stress problems and, according to one study , even heart health problems.

Researchers at the University of Hong Kong have dubbed this phenomenon the "anxious Monday" effect. They suggest that dysregulation of the body's stress management system, which is known to lead to heart disease, is linked to the start of the week.

The curious thing is that this occurs regardless of employment status, the researchers said, meaning they have also detected it in retired people, who do not have to go to work on Mondays.

The study authors also note that previous research has shown a 19% increase in heart attacks and sudden cardiac deaths on Mondays, and they believe the Monday spike in heart attacks is unlikely to be random.

Lead author Professor Tarani Chandola of the Department of Sociology in the Faculty of Social Sciences at the University of Hong Kong (HKU) says: "Mondays act as a cultural 'stress amplifier.'"

“For some older adults, the transition of the week triggers a biological cascade that persists for months. It's not about work; it's about how deeply ingrained Mondays are in our stress physiology, even after we finish our careers,” says Chandola.

Feelings of stress and anxiety are linked to cardiovascular disease through a key biological mechanism called hypothalamic-pituitary-adrenal (HPA) axis dysregulation.

The HPA axis is the body's primary way of responding to stress and produces the release of cortisol (known as the stress hormone) in the body.

Dysregulation of the HPA axis is characterized by excessive levels of cortisol production, which has previously been linked to an increased risk of heart disease and death, the researchers explain. It's also known to contribute to hypertension, insulin resistance, and immune dysfunction.

The study team set out to examine whether " HPA axis dysregulation is greater on Mondays than on other days, and whether this association is stronger among working adults than among nonworking adults."

Researchers evaluated data from more than 3,500 older adults participating in the English Longitudinal Study of Ageing, including hair samples that showed cortisol levels in the participants' bodies.

People who reported feeling more anxious on Mondays had 23% higher cortisol levels in their hair samples than those who felt anxious on other days.

This was also observed among retirees, challenging assumptions that workplace stress alone explains the 'Monday blues.'

The researchers conclude: "This study found strong evidence of an association between reporting anxiety on Mondays and HPA axis dysregulation. The association of anxious Mondays with subsequently measured HPA axis dysregulation was evident among both working and nonworking older adults, with no reduction in the association among nonworking older adults."

The findings suggest that social patterns—not just job demands—are embedded in human physiology, with lasting health risks , the researchers said.

Researchers hope that addressing Monday-specific stressors could pave the way for new strategies to combat heart disease.

"Hospitals and clinics should prepare for a higher number of CVD events on Mondays ," they conclude.