Jo was a melatonin chronobiology pioneer and giant. She recognised the power of melatonin, measured it, applied it to problems such as jet lag and delayed sleep-wake phase disorder, its potential in restoring entrainment of blind people to the 24 hour day as well as the relevance of circadian rhythms to metabolism. Pioneering science.  She founded a successful company before spin-off was a word and established Surrey as a centre for chronobiology. She recognised the importance of critical mass and recruited a next generation of chronobiologist, including me, to Surrey, and I have never regretted it. Jo retired, I think in part because she wanted to give this next generation a chance to grow and be independent. After her retirement, she continued to carefully follow the melatonin and circadian literature and enjoyed commenting on popular papers the conclusions of which she agreed or disagreed with. She also had a sense of humour that was born out of her sharp and critical intellect. Jo is a role model indeed. 

Derk-Jan