👶 Zara Kadir, a psychotherapist, highlights adrenarche as a reason for eight-year-olds' mood swings, noted in her clients aged 7-10. She suggests that adrenarche, a hormonal stage that can begin before the more obvious signs of puberty, may play a part. © ShutterstockKadir describes the challenge as children developing bigger feelings while their ability to manage those emotions is still developing. A 2020 systematic review published in JAMA Pediatrics found that the average age at which girls began developing breasts fell by almost three months per decade between 1977 and 2013. Parents who notice signs before eight, or who are worried about their child’s development or behaviour, should speak to their GP.