Sudden lifestyle changes sparked by the onset of the COVID-19 pandemic have triggered more frequent and severe attacks for migraine sufferers, Sydney researchers have found.

However they also identified a series of factors associated with decreased frequency of headaches, including consuming less alcohol and processed or fast foods and upping exercise levels.

Almost half of 711 patients surveyed in June and July last year experienced an increase in migraine frequency at the onset of COVID-19 restrictions, according to the study led by Sydney neurologist Dr Bronwyn Jenkins.

Some 41% reported greater severity of attacks and 42%, an increase in their impact, in the findings released on Sunday.