Sleep physiology, pain and mood symptoms of 8 patients with idiopathic osteoarthritis of the hands who complained of morning symptoms were compared to 7 age and sex matched subjects with similar joint pathology, but who did not complain of morning symptoms. The "AM Symptoms" group had sleep related (nocturnal) myoclonus, associated with increased morning peripheral joint tenderness and decreased grip strength, whereas the "No Complaint" group had improved mood in the morning.