Having lots of figures and tables in my document, I have created two commands \source and \notes to format the source of the figure/table and add any notes (see MWE). The body text has double line spacing, how can I reduce the line spacing to one-half or single line spacing in my newly defined \notes environment?
\documentclass[a4paper, 12pt]{report}
\usepackage[english,frenchb]{babel}
\usepackage{graphicx}
\usepackage{adjustbox}
\usepackage{subcaption}
\linespread{1.6} %Setting double spacing for document
%---- Create 'source' and 'notes' commands ----%
\newcommand{\source}[1]{\vspace{-1.5em}
\captionsetup{justification=justified} \caption*{\raggedright\textnormal{\footnotesize{\textit{#1}}}}}
\newcommand{\notes}[1]{\vspace{-0.5em}
% Would like 1.5 spacing for 'notes' environment
\captionsetup{justification=justified} \caption*{\textnormal{\scriptsize{\textit{#1}}}}}
\linespread{1.6}
\begin{document}
\begin{figure}[h!]
\begin{center}
\caption{A figure}
\resizebox{!}{70mm}{\includegraphics{{example-image-a}}}
\end{center}
\source{Source : source of figure.}
\notes{Notes : Some very long notes spread over several lines of which I would like to reduce linespacing. Some very long notes spread over several lines of which I would like to reduce linespacing. Some very long notes spread over several lines of which I would like to reduce linespacing. Some very long notes spread over several lines of which I would like to reduce linespacing.}
\end{figure}
Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text. Lots and lots of text.
\end{document}

