I did the test yesterday and it's between 15 and 45 minutes on average. The test measures performance as you go so will get harder/easier depending on the answers you give which accounts for the fluctuation in average time. That being said - the test isn't timed so you can take as long as you need. It also saves your answers, so if you start and find you need a break to can just close the test and come back to it after a break.It explains this at the beginning too, clicking the link on the email doesn't commit you to taking the test there and then. Hope you get better soon and good luck.