He tries to settle his thoughts. Being a telepath, he's got a very active mind, more than a normal human. If he had been hooked up to an EEG machine, a doctor would mistake the readout for a human having a seizure.
Once the somnicin hits him, his eyelids close halfway, feeling sleepy...but not out. He probably could snooze lightly on that but he probably wouldn't dream. Charles shakes his head at the cobwebs, giving Eames a half awake look.