\makeatletter
\def\sect{\@dblarg\@sect}
\def\@sect[#1]#2{%
\par%
\nolinenumbers%
\section[#1]{#2}%
\linenumbers%
}
\def\subsect{\@dblarg\@subsect}
\def\@subsect[#1]#2{%
\par%
\nolinenumbers%
\subsection[#1]{#2}%
\linenumbers%
}
\def\subsubsect{\@dblarg\@subsubsect}
\def\@subsubsect[#1]#2{%
\par%
\nolinenumbers%
\subsubsection[#1]{#2}%
\linenumbers%
}
\makeatother