Sleep deprivation gets blamed for some of the worst disasters of the twentieth century, from the Chernobyl meltdown to the Challenger shuttle explosion, and Robert Winston opens this BBC program with that claim before testing what poor sleep actually does to ordinary people. A group of self-professed bad sleepers goes through a sleep lab, wired up overnight so their patterns can be measured against what they report feeling the next day. Winston cites the statistic that one in five motorway accidents is linked to tiredness at the wheel, then works through the science of what sleep is for and why so many people fail at something the body should do automatically. Viewers watching the original broadcast could press a red button to answer an on-air questionnaire and get a personalized sleep profile, a device that shaped the program's advice around different sleeper types rather than a single fix. The film stays away from sleeping pills, favoring behavioral changes drawn from the lab results instead.