The past two years have caused widespread disruption, anxiety, loss and grief worldwide—but a new University of Otago, Christchurch, study has identified a concerning link between ongoing COVID‑19 disruption and worsening mental health for those most at risk.

The international study, involving hundreds of New Zealanders, has sparked a call for more public health awareness of the effects of COVID‑19 on mood, and for the issue to be taken more seriously.

A researcher from the New Zealand arm of the international study, Professor Richard Porter, Head of the Department of Psychological Medicine, says that amongst study participants previously diagnosed with a mood disorder, nearly 40% self-reported moderate to severe depression during Aotearoa New Zealand's first lockdown period in 2020.

"Although we expected to see disruption from changes in circadian rhythm negatively affecting mood in these participants, we were surprised how severe their self-reported symptoms were.

"Our results show there is a definitive link between COVID-related disruption to circadian rhythms and worsening mental health in those with existing mood disorders, namely depression and bipolar disorder," Professor Porter says.

The questionnaire study, published in the Canadian Journal of Psychiatry, was conducted from April to June 2020, incorporating much of Aotearoa New Zealand's first Level 4 lockdown. It was conducted by researchers from six different countries—New Zealand, Australia, Scotland, Canada, the U.S. and Holland. More than half (521) of the total 997 participants were from New Zealand. Fifty percent of the total cohort had been formally diagnosed with bipolar disorder; 50 percent with depression.

Professor Porter says while only 12% of participants self-reported minimal depressive feelings from COVID‑19 disruption to their circadian rhythms, 20% reported having mild depression; 27% moderate depression; 21% moderate-to-severe depression and 18% severe depression.

"The fact that nearly 40% of these already vulnerable people reported their symptoms as moderate to severe raises concern.

"These results show it's important we recognize the vulnerability of those with mood disorders when faced with disruptive situations such as COVID‑19, earthquakes or other major upheavals in their lives and consider doing more to help them maintain their mood and mental health. With experts now predicting COVID‑19 could be with us for the next five years, including the potential prospect of future lockdowns, more emphasis is needed from a public health standpoint to help people with mood disorders better regulate their circadian rhythms and maintain good mental health."

Professor Porter says participants reported the worst causes of COVID‑19 disruption as an inability to go to work, forced isolation at home, not being able to socialize as normal, and struggling to maintain their usual eating and sleeping patterns. These factors negatively affected mental health determinants such as their general mood, outlook on life, positivity and irritability levels.

He says practical responses, such as giving those most at risk the tips, tools and strategies to allow them to better support their circadian rhythms and mental health should be a priority for health professionals delivering their care.

Professor Porter's research team is currently involved in several clinical trials examining practical methods to improve and treat mood disorders.

Psychotherapy is being used to help regulate social and circadian rhythms—with participants recording meal times, social interactions, sleep and waking times, to better scaffold and regularize their activities and support circadian patterns.

The use of light therapy is also being trialed, as well as the use of blue-blocking glasses before sleep to help suppress melatonin secretion.