Humans need sufficient sleep to function. The conventional wisdom is that we need around 8 hours each night to be at peak performance.But for people with idiopathic hypersomnia, or IH, no amount of sleep can shake a profound feeling of sleepiness. Some can sleep for over 24 hours, despite using stimulants and multiple alarm clocks. Others fall asleep while driving or doing other daily activities.IH is rare. It affects just a small fraction of 1% of people, and the underlying cause is unknown. Now, scientists are doing more research into the condition, thanks in large part to patients organizing and advocating for better treatment options. Unlocking what causes this excessive sleepiness may be key to understanding the bigger picture of how the body enters and wakes from sleep.Ira discusses the science of sleepiness with Dr. Quinn Eastman, science writer and author of The Woman Who Couldn’t Wake Up: Hypersomnia and the Science of Sleepiness, and Diana Kimmel, co-founder of the Hypersomnia Alliance, and board member of the Hypersomnia Foundation.Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.