Differential effects of bifrontal tDCS on arousal and sleep duration in insomnia patients and healthy controls by Frase, L, Selhausen, P, Krone, L, Tsodor, S, Jahn, F, Feige, B, Maier, JG, Mainberger, F, Piosczyk, H, Kuhn, M, Klöppel, S, Sterr, A, Baglioni, C, Spiegelhalder, K, Riemann, D, Nitsche, MA, Nissen, C