Sleep in craniopagus twins

Two craniopagus twins sharing some common cerebral circulation but no common brain structures were recorded polygraphically and continuously observed for behavioral sleep states and wakefulness. The observations lasted 9.5 h when the twins were 12 weeks postgestation and for 24 h at 16 weeks post gestation, or approximately 4 weeks postterm. Sleep onsets were synchronous 67% of the time (+/- 5 min), but arousals were synchronous only 38% of the time (+/- 5 min) at 16 weeks postgestation. The recordings reported here are the longest ever made of craniopagus twins. This report is consistent with some interdependence of the sleep of each twin on the other. Possible reasons for this are discussed.