ALAN CHAVEZ usually thinks nothing of abseiling down a 30-storey building to clean the windows. But after his daughter Luanna was born 11 months ago, the ''rope access technician'' became a bit concerned.

The trouble was fatigue caused by too little sleep. After a broken night, he had to get up at 5am to go to work. ''It's potentially dangerous work but if you do things in a good way and concentrate you'll be fine,'' he said. ''That's pretty hard to do when you're really tired.''

High-rise window cleaner Alan Chavez with his 11-month-old daughter Luanna.

A lot of fathers of infants are suffering fatigue, a new study shows, and it can have ramifications for workplace safety, especially for men who are doing physically demanding work or handling machinery.

The study's lead author, Gary Mellor, a senior lecturer in the school of health and human sciences at Southern Cross University, has called for employers to be more aware of and sympathetic to the fatigue experienced by men during early fatherhood and do what they can to help.