Health & Wellness Halo Sun ,09 2424 2 months ago Last Updated : 07:00 AM Michel Siffre, 85, Dies; Descended Into Caves to Study the Human Mind He was a pioneer in chronobiology, the study of how our bodies understand the passage of time. HALO NEWSLETTER Keep reading HALO with a Free Subscription unlock this story instantly and join members and pros reading HALO daily -It's Free SIGN UP LOGIN