Think, then, what it also must feel like to have severe muscle and joint pain, headaches and sore lymph nodes. On top of that, you can't concentrate, and you're tired, really tired, most of the time -- a sense of exhaustion that just won't go away, no matter how long you sleep.
Some half a million Americans don't have to imagine it. They feel that way day after day, year after year.
Called chronic fatigue syndrome, this illness comes with a laundry list of symptoms and complaints, but an absence of absolute answers. Cause? Unknown. Diagnosis? Uncertain. Treatment options? Unclear.
But the effects? Very real.
"I missed an entire quarter of my junior year [in high school] because my mom couldn't get me out of bed in the morning," says 27-year-old Jessica Klein, of Sterling, Va. She dropped out of college for a while for the same reason, and earlier this year she had to quit her job as a self-described "computer guru."
"They wanted me to stay for 8 1/2 hours a day, plus a 45-minute commute, and I couldn't stay awake that long," says Klein, who has lived with this condition since she was 8 years old, although it wasn't diagnosed as chronic fatigue syndrome (CFS) until recently.
"It's not a normal tired," she says. "You run into a wall. You can't keep your head up or your eyes open." Klein describes it as "having bricks tied to your arms and legs, to your eyelids and the back of your head."
Sometimes, she says, she's afraid to fall asleep because she might not be able to get up in time for appointments.
The crushing tiredness apparently is universal, but other symptoms are not the same for everyone, says Leonard Jason, director of the Center for Community Research at DePaul University in Chicago and a member of the federal government's CFS Advisory Committee.
Some sufferers feel faint when they stand up, others have feverish symptoms, and for some, inflammation is the hallmark.
"When you look at a group of people with CFS, you never find 100 percent of the people with the same thing," Jason says.
Their illness takes different paths to the same endpoint: "They feel very, very sick, extremely sick, extremely debilitated," he says.
If the constant fatigue lasts for six months or more, with at least four other symptoms -- such as concentration problems, muscle pain, sore lymph nodes or disturbed sleep -- then a diagnosis of CFS is justified, Jason explains.
Still, no specific diagnostic tests for CFS are available, according to the U.S. Centers for Disease Control and Prevention, leaving doctors to diagnose by exclusion, meaning they resort to ruling out other possibilities.
Medical treatment generally focuses on relieving whatever a person's specific symptoms might be, but it also can include such options as exercise, lifestyle changes and behavioral therapy. Support groups abound.
For many, though, just getting diagnosed correctly is a struggle.
As Klein explains, "When we come in and start complaining, [doctors] basically think we're nuts, and that makes me mad."
Part of the problem may lie with the name -- chronic fatigue syndrome -- which many CFS experts say is inadequate and disparaging.
"Over 90 percent of the patient community hates that name," says Jason, adding that it prompts many doctors to "roll their eyes and not take it seriously."
"A name that sounds kind of technical or medical will have people feeling that the person is sicker than if the name is a little bit trivializing -- like saying you have 'chronic cough syndrome' rather than bronchitis or emphysema," says Jason, who has published research on the effect of the name "chronic fatigue syndrome."
However, CFS might not be the official designation for this illness much longer.
A group of scientists and patients has been working for the past two years to come up with a new name and expects to present it to the federal government's CFS Advisory Committee in the next few months. With committee approval, it would go on to the U.S. Secretary of Health and Human Services, Tommy Thompson, who can make it official, Jason says.
The new name -- neuroendocrineimmune dysfunction syndrome, or NDS -- better represents the illness, Jason says.
"The term is broad enough to encompass the most commonly reported symptoms [which] are associated with or referable to the neurologic, neuroendocrine and immunologic systems," states a paper prepared by the group proposing the name change.
Continued use of the term "syndrome" recognizes that it's a "collection of signs and symptoms that in their totality define this illness," the group says.
And, the group adds, that also should help NDS to gain acceptance by the medical community.
"If you feel you have a medical illness and are looking for strategies to help," Jason says, "you don't want to be referred to a psychiatrist."
March is National Chronic Fatigue Syndrome Awareness Month.