About 25% of Americans experience acute insomnia each year, but about 75% of these individuals recover without developing persistent poor sleep or chronic insomnia, according to a study from researchers at the Perelman School of Medicine at the University of Pennsylvania presented at SLEEP 2018, the 32nd Annual Meeting of the Associated Professional Sleep Societies LLC (APSS).

The new study offers the latest data on the prevalence of acute insomnia, which is characterized by difficulty falling asleep or staying asleep for as little as 3 nights per week for at least 2 consecutive weeks up to 3 months. Insomnia becomes chronic when it occurs at least 3 nights a week for more than 3 months.

“Whether caused by stress, illness, medications, or other factors, poor sleep is very common,” said senior author Michael Perlis, PhD, an associate professor of psychiatry and director of the Behavioral Sleep Medicine program. “These findings reveal new insights about the paths that acute insomnia takes and can inform interventions that target poor sleep and help people recover sustained sufficient sleep.”

Although some studies have offered the prevalence of insomnia symptoms in large populations, to date this is the first study to offer data on transitions of good sleepers (GS)—defined as those needing fewer than 15 minutes to fall asleep and/or who spend fewer than 15 minutes awake during the night on 5 or more nights per week. The study specifically determines how GS transition to acute insomnia (AI), to persistent poor sleep (PPS)—ie, recurring bouts of AI without sustained recovery or turning to chronic insomnia (CI), and how many of those affected by AI recover.

A total of 1,435 adults were recruited nationwide and tracked for 1 year during 2015-2017. They were verified as GS over the first 3 months of the study and assessed on a daily, weekly, and monthly basis. The subjects kept a daily sleep diary for the duration of the study, allowing for a uniquely detailed level of insight into how sleep varies from day to day. Also, regular assessments were made regarding participants’ daytime function, stress and life events, and medical and mental health.

Among the 25% experiencing AI, about 75% of subjects recovered good sleep within 12 months, while 21% remained poor sleepers with recurring bouts of AI, and about 6% developed CI. No significant differences were observed along racial, ethnic, or gender lines, or among people of varying incomes or BMI.

The new data provide researchers with how many people experience AI each year, as well as how those cases progress, laying the groundwork for additional research now underway to assess what factors predict recovery (resilience) and non-recovery (PPS or the new onset of CI).