Primary intracerebral hemorrhage during asleep period.

Background: The onset of intracerebral hemorrhage (ICH) has a circadian variation, with a lower risk during the asleep period. It is unclear, however, whether ICH during the asleep period differs from that during the awake period in pathophysiologic nature. The purpose of this study is to elucidate the incidences and clinical features of ICH during the asleep period.
Methods: We studied 129 consecutive patients with primary ICH and classified them into two groups according to the circumstance of their stroke onset, either during the awake period (awake ICH group) or the asleep period (asleep ICH group). Demographic and clinical characteristics were then compared between the two groups.
Results: Of the patients, 19 (14.7%) had ICH during the asleep period. The mortality rate at 1 month after the stroke was significantly higher in the asleep ICH group than in the awake ICH group (21.1% v 4.9%, P = .0325). The hemorrhage volume in the asleep ICH group was also significantly larger than that in the awake ICH group (mean volume, 32.6 mL v 16.7 mL, P = .0122).
Conclusions: Our findings indicate that ICH during the asleep period may be more detrimental compared with ICH during the awake period, causing larger hematoma and higher mortality rates.