Women are twice as likely to suffer from severe stress and anxiety as men, according to a major study.
Anxiety disorders are among the most common mental conditions in the Western world.
Yet experts say they remain woefully understood.
Now scientists at Cambridge University have found that women are 1.9 times as likely to suffer as men, a trend which persists throughout their lifetimes.
The researchers believe this may be because women now often have to juggle work, family and children - causing them to suffer from mental burn-out.
The study also showed that both men and women are at peak risk below the age of 35.
The experts, whose findings are published in the journal Brain and Behaviour, reviewed 48 studies from around the world.
The team also discovered that people from Western Europe and North America are far more likely to suffer from stress and anxiety than those in the developing world.
Study leader Olivia Remes, of the Department of Public Health and Primary Care, said:
"Anxiety disorders can make life extremely difficult for some people and it is important for our health services to understand how common they are and which groups of people are at greatest risk.
"By collecting all the data together, we see that these disorders are common across all groups, but women and young people are disproportionately affected."
Miss Remes suggested that social changes may be behind this gulf between men and women.
She said: "While in the past women were more likely to stay at home and be responsible for the family, they are now more likely to hold down a job while also bringing up children. Women are more likely to have employment now than in the past, but also more likely to look after the family and elderly or disabled relatives.
The burden of all these things falls to women."
Miss Remes added that while more research is needed, there may also be links to psychological differences between the sexes.
"When women are subjected to stress they are more likely to internalise it and develop anxiety," she said. "They tend to ruminate about what has gone wrong.
"Whereas men externalise - they react, and this means they are more likely to develop other problems, such as alcohol or drug issues.
"There may be biological differences - it could be because of differences in brain chemistry or hormones."
Co-author Dr Louise Lafortune said: "Anxiety disorders affect a lot of people and can lead to impairment, disability, and risk of suicide.
"Although many groups have examined this important topic, significant gaps in research remain."
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youth services: (06) 3555 906 (Palmerston North and Levin)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Samaritans: 0800 726 666 (available 24/7)
If it is an emergency and you feel like you or someone else is at risk, call 111.