March 11, 2009 — Almost half of patients with insomnia have suffered from sleep problems for 3 years or more, and three-fourths report at least 1 year of insomnia symptoms, according to a report in the March 9 issue of Archives of Internal Medicine.

Lead author Charles M. Morin, PhD, from the Université Laval and Centre de Recherche Université Laval–Robert Giffard, in Quebec, told Medscape Psychiatry that the study's most important findings were that patients with insomnia are unlikely to remit spontaneously, that the most frequent long-term trajectory for untreated insomnia is that symptoms will persist, and that recurrence is common even in patients with spontaneous or treatment-induced remission.

Dr. Morin and colleagues conducted the first 3-year longitudinal natural history study of insomnia in adults with insomnia syndrome at baseline vs subjects who had some insomnia symptoms but not full-blown insomnia.

The researchers annually evaluated insomnia persistence, remission, and relapse in 388 adults (average age, 44.8 years). Insomnia syndrome was defined as insomnia symptoms at least 3 nights per week for at least 1 month and substantial distress or daytime impairment.

Majority Report Symptoms Lasting at Least 1 Year

The 3-year data showed that 74% of subjects reported insomnia for at least 1 year, and 46% reported insomnia persisting over the entire 3-year period. Patients who had insomnia syndrome at baseline were more likely to have insomnia persist over the entire period than those who had only insomnia symptoms (66.1% vs 37.2%).

Insomnia went into remission in about 54% of patients but eventually recurred in 26.7%.

"Individuals with subsyndromal insomnia [insomnia symptoms] at baseline were 3 times more likely to remit than worsen to syndrome status, although persistence was the most frequent course in that group as well," the authors write.

After 1 year, 38.4% of the 269 individuals with baseline symptoms of insomnia were classified as good sleepers, 48.7% still had insomnia symptoms, and 12.9% had progressed to insomnia syndrome. Results were similar after the second and third year of follow-up.

However, at 1 year, only 17% of the 119 participants with insomnia syndrome at baseline had improved to "good-sleeper" status, 37% had improved to the point of having only some symptoms of insomnia, and 46% still had full-blown insomnia syndrome.

Experts Urge Longer Follow-up

Dr. Morin also noted that chronic insomnia increases the risk for other problems, including depression, anxiety disorders, and substance abuse. He also said that a problem with many other insomnia studies has been the short duration of follow-up.

"Our data show that insomnia can be very persistent. Even if treatment is effective in the short term, we should be meticulous about follow-up, since the patient may have recurrence and might need longer-term treatment," Dr. Morin said.

He urged clinicians to give insomnia complaints a higher priority and to evaluate sleep along with other problems such as anxiety or depressive symptoms as part of the routine clinical evaluation.

Sleep expert David N. Neubauer, MD, from the Johns Hopkins Sleep Disorders Center, in Baltimore, Maryland, told Medscape Psychiatry that the Morin study is an important achievement that "will be much quoted" by sleep researchers and clinicians.

Take It Seriously, Treat It Early

"The take-away message is, take insomnia seriously. Treat it sooner rather than later. Insomnia is not just something that occurs in response to the environment. Also, remember that insomnia increases the risk of mood and anxiety disorders," Dr. Neubauer said.

He also emphasized that the patient with true insomnia will report sleep problems and various daytime difficulties, but not necessarily daytime sleepiness.

"Fatigue and concentration problems are common complaints, but daytime sleepiness is not. People with insomnia are different from those who don't have insomnia, and we think that whatever causes their nighttime sleep problems also affects them during the daytime," Dr. Neubauer said. "The daytime problems are not just the result of getting too little sleep the night before. In fact, most people with chronic insomnia are not sleepy during the daytime."

"For the patient with situational or short-term insomnia, immediate treatment is not necessarily indicated. But if the patient reports both insomnia at night and daytime problems, clinicians should not take those complaints lightly. If patients meet the requirements for a diagnosis of insomnia syndrome, treat them, or you will see them again in 2 or 3 years still suffering from the same symptoms," Dr. Morin said.

This study was supported by grant MT42504 from the Canadian Institutes of Health Research. The authors report no relevant conflicts of interest.

Arch Intern Med. 2009;169:447-453. Abstract