Rails devise: user_signed_in? not working

I have this in my view:

<% if user_signed_in? %>
<%= current_user.email %>
<% else %>
<%= link_to "Sign in", new_user_session_path %><br />
<%= link_to "Opret", new_user_session_path %><br />
<% end %>

But when have signed in as a user: I still get the links in view:

<%= link_to "Sign in", new_user_session_path %><br />
<%= link_to "Opret", new_user_session_path %><br />

Why is the helper not working?