body clocks: the biology of time for sleep, education and work  as featured in the sunday times, the daily telegraph, the evening standard, daily mail (online), bbc five live, metro, tes <br>our body's clocks make the difference between happiness and depression, health and illness, and even life and death. <br> <br>the brilliant scientist paul kelley, along with renowned journalist sian griffiths, makes a compelling case for all organisations to allow people to work and study the hours that suit their personal circadian rhythms. that way, they argue, we would all be more productive and a great deal of ill health would be avoided.