Insomnia is underrecognized in patients with cancer. By identifying clinical correlations and predisposing factors of insomnia, interventions may be initiated to treat insomnia.

Consecutive patients referred to palliative medicine services were screened with a single question. Patients answering affirmatively completed the Insomnia Severity Index (ISI). Patients were screened for depression, fatigue, and pain. Spearman correlation was performed for associations.

Of 715 consecutive patients, 102 had sleep problems and 64 had clinical insomnia by the ISI criteria. Insomnia correlated with depression (r = .32), pain (r = .29), and tiredness (r = .40) but not with age or precipitating factors.

Insomnia severity moderately correlates with depression, pain, and tiredness. We found no association of insomnia severity with age or medications.

Insomnia, pain, depression, and tiredness are a symptom cluster.