问自定义中间件检查模型自定义函数Laravel5.1返回的值时出错

EN

public function isActivated()
{
    return $this->estado;
}

Fatal Throwable Error: 
Fatal Error: Call to a member function isActivated() on null

<?php

 namespace App\Http\Middleware;

 use Closure;
 use Illuminate\Contracts\Auth\Guard;

 class RedirectIfNotMailActivated
{
/**
 * The Guard implementation.
 *
 * @var Guard
 */
protected $auth;

/**
 * Create a new filter instance.
 *
 * @param  Guard  $auth
 * @return void
 */
public function __construct(Guard $auth)
{
    $this->auth = $auth;
}
/**
 * Handle an incoming request.
 *
 * @param  \Illuminate\Http\Request  $request
 * @param  \Closure  $next
 * @return mixed
 */
public function handle($request, Closure $next)
{
    if ( ! $this->auth->user()->isActivated()) {
        return redirect('/login')
            ->with('mensaje',
                   '¡Lo sentimos, no ha confirmado su cuenta aún!');
    } else {
        return $next($request);
    }
 }
}

Route::post('/login', [
        'middleware' => 'activated.email',
        'uses' => 'loginController@store'
]);