draw_day_night_rectangles
=========================

Description
-----------

This function inks the day with a light color and night with a darker
color

Usage
-----

.. code:: r

   draw_day_night_rectangles(
     df,
     p,
     light_start = 7,
     light_end = 19,
     light_offset = 0,
     day_color = "yellow",
     night_color = "grey",
     light_cycle = c("Day", "Night")
   )

Arguments
---------

-  ``df``: data frame
-  ``p``: plot object
-  ``light_start``: start of light cycle
-  ``light_end``: end of light cycle
-  ``light_offset``: offset of light cycle from start of day (for
   zeitgeber time always 0)
-  ``day_color``: color for light phase (day)
-  ``night_color``: color for dark phase (night)
-  ``light_cycle``: choose Day or Night