Body Clock: What Makes Us Tick?

We all have a biological clock ticking away inside us that governs our daily rhythms. This affects our health as much as our diet and whether we exercise. So what can we do to manage this internal clock better?To find out, evolutionary biologist Ella Al-Shamahi locks former commando Aldo Kane in an abandoned nuclear bunker with no way of telling the time - for ten days. Monitored around the clock by a team of scientists, he carries out a barrage of tests to uncover exactly what makes our body clock tick.