Updated February 29, 2016
Chronic insomniacs rarely feel sleepy, while people with sleep apnea can doze off anywhere—even behind the wheel.

Chronic insomniacs rarely feel sleepy, while people with sleep apnea can doze off anywhere—even behind the wheel.(THINKSTOCK/CORBIS)It may not seem this way on the surface, but to a sleep doctor there's a big difference between someone feeling "tired" and someone feeling "sleepy."

  • Tired means you lack energy, have trouble focusing, and feel "out of it" all the time.
  • Sleepy means you're yawning, nodding off, and can't keep your eyes open.

How you feel during the day is a key piece of information for doctors because different sleep disorders have different symptoms. Insomnia patients are constantly tired but rarely feel the urge to sleep during the day. Sleep apnea and narcolepsy patients are tired too, but they are constantly fighting off sleep.

The clearer you are in describing your symptoms, the quicker your doctor can get you the help you need. Insomnia isn't immediately life-threatening, but sleep apnea, which often goes undiagnosed for years, can raise the risk of heart disease, stroke, and high blood pressure.

What Insomnia Feels Like


It's possible to be exhausted and still not able to sleep Read moreMore about daytime sleepiness

The risk of people with sleep apnea falling asleep at the wheel is also very real. People with the disorder are twice as likely to have a car crash, and three to five times as likely to have a serious crash involving personal injury, according to a 2007 study by the University of British Columbia Sleep Disorders Program in Vancouver.

While sleep apnea patients often omit the critical word "sleepy" when describing their daytime symptoms, insomniacs rarely make the mistake of including it—probably because they just don't feel like they can sleep. They are well aware, instead, of being up half the night and feeling exhausted and unfocused during the day.

Saying that you are so sleepy you have to nap in your office during the day hopefully will sound the alarm for your doctor. Just saying that you're tired or run down might leave you with the wrong diagnosis—or none at all.