The Earth Observation Group
at the US National Centers for Environmental Information
has long created night-lights maps of Earth by combining satellite data, which this site aims to make available using Google Maps' API
while Google doesn't incorporate this into their own offer.
Until 2011 saw the launch of a new satellite, these night-lights mosaic pictures relied on technology from the 1970s (see "2010" below). In 2012, NASA 'beautified' a mosaic of the new satellite's images by colouring them yellow and putting them on a blue daytime background (see "2012"). While NASA's picture shows even villages' lights, subtle differences in cities are lost. Hence, the more up-to-date imagery (see "2015" and later) was converted with different brightness mappings.
Make your choice using the following example pictures showing the eastern Mediterranean and the south-west of London:
By the way, the NCEI's EOG also allows you to download very recent night-time mosaic pictures
(though with clouds and gaps). Of course, while these images are unparalleled on a global scale, the astronauts on the ISS have taken some fascinating photos
at a higher resolution and with original colour like this one showing that Berlin is still divided in terms of street lighting