A study published in 2014 stated that a sleepy brain presents symptoms similar to those developed in cases of unilateral or hemispatial neglect syndrome. In these types of disorder (caused by brain damage) patients lose sense of space on one side of the body. In even more serious cases, patients can only wear one side of the body, for example.
The scientists involved in the study looked at volunteers who were in a dark room and seated in an armchair. As they became sleepy, the electrodes placed in their bodies were analysed and quantified the reaction time to the sounds on the left and right side. The experts concluded that those who were more sleepy were less attentive to the sounds issued on the left side.
For Masud Rusain, a neurologist at the university of Oxford, the study proves that “a sleepy brain behaves like the brain of a patient with injury”, citing as an example the consequences of a stroke.