Background: The prevalence of sleep disorders increases with age. Sleep disorders may have serious health implications and may be related to serious underlying diseases. Many older people use hypnotics, like benzodiazepines, although these medications have serious side effects and often lead to habituation. Acetaminophen is one of the most frequently used off-label drugs for sleep disorders, although little is known about its effects. Our objective is to investigate whether acetaminophen is effective in treating self-reported sleep disorders in older people. Methods/Design: Participants, aged 65 years or older (n = 150), who have sleep disorders will be randomized for treatment with either acetaminophen 1000 mg or placebo, once daily at bedtime in a double-blind design. Eligible patients should be able to give informed consent, should not be cognitively impaired (Minimal Mental State Examination (MMSE) score >= 20), should not have pain, and should not use acetaminophen on a regular basis because of pain complaints. The study will take three weeks to complete. During these three weeks, the participants register their sleep behavior in a sleep diary. The participants will use the study medication during the second and third week. The primary endpoint will be the self-reported sleep disorders at the end of week three, as measured by means of the Insomnia Severity Index (ISI). To validate these subjective sleep parameters against objectively measured indices of the sleep-wake pattern, we will measure the periods of wakefulness and sleep in a subgroup of participants, using an actigraph worn on the wrist during the entire study period. Discussion: The proposed study will contribute to our knowledge about the treatment of sleep disorders in an older population. There is a need for treatments for sleep disorders without serious adverse effects. Acetaminophen might be a simple and inexpensive alternative for the regimes that are currently used with older people.