Environmental influences on activity patterns in altered states of consciousness

Background and purpose: To evaluate in disorders of consciousness (DOC) circadian variations in motor patterns and their possible synchronization with physiologically regulated light variations and/or a social environmental factor, i.e. presence and actions of other persons. Methods: Actimetric and ambient light levels recordings were obtained during 4–9 days in two patients with traumatic brain injury (TB1 and TB2) in a minimally conscious state (MCS), one MCS (AI1) and one comatose (AI2) anoxic‐ischaemic patients. Environmental changes were automatically recorded using a video system. Results: Minute light variations correlated with motor activity in all patients. However, motor activity was significantly higher during day than nighttime and correlated with social environmental changes, in patients TB1 and TB2 only. Conclusions: Night‐day circadian variations in motor activity patterns and influence of social stimulations were observed in traumatic MCS patients only. Nonetheless, rapid light variations may temporarily promote increased arousal, and consequently motor activity, in all DOCs.