We all get tired, but for some people falling asleep can happen so easily it's a medical condition that needs to be treated -- especially for their safety.
Andrea Shock knew she was tired a lot, but when the 26-year-old fell asleep behind the wheel she knew something more serious was going on.
"I don't remember falling asleep, but I do remember waking up to my sister's screams," Shock said. "That's the only thing I remember about the crash."
Turns out the Waterloo woman has narcolepsy -- a sleep disorder that causes excessive sleepiness and frequent daytime sleep attacks.
"They are sitting in a room and reading something and they fall asleep all the time," said Dr. Sangeeta Goel-Shah, a Covenant Clinic neurologist. " If they are doing nothing, they are sitting on a chair and fall asleep, that's not normal."
So how do you know if your sleepiness is something more serious?
"They go into REM, which is a deep sleep, and it only takes a fraction of a second for them to go into a deep sleep and then at that time they are totally, deeply asleep," said Goel-Shah. "They can do that for five minutes and would wake up and feel totally refreshed from that."
Especially now that she has a 5-month-old, Andrea is happy to be able to manage her condition.
"I mean, it can be dangerous if you're driving and you fall asleep," she said. "You could get in a car wreck, you could kill somebody else, you could kill yourself so it's something that can affect your life."
Doctors say medications are available to treat narcolepsy with few side effects.