  This paper is devoted to the following class of nonlinear fractional
Schr\"odinger equations: \begin{equation*} (-\Delta)^{s} u + V(x)u = f(x,u) +
\lambda g(x,u), \quad \text{in}\: \mathbb{R}^N, \end{equation*} where $s\in
(0,1)$, $N>2s$, $(-\Delta)^{s}$ stands for the fractional Laplacian,
$\lambda\in \mathbb{R}$ is a parameter, $V\in C(\mathbb{R}^N,R)$, $f(x,u)$ is
superlinear and $g(x,u)$ is sublinear with respect to $u$, respectively. We
prove the existence of infinitely many high energy solutions of the
aforementioned equation by means of the Fountain theorem. Some recent results
are extended and sharply improved.
