I enjoy taking occasional power naps after lunch or in the afternoon. I rarely fall asleep, but when I do, it really is refreshing.
One tool I discovered are Binaural Beats:
A binaural beat is an auditory illusion perceived when two different pure-tone sine waves, both with frequencies lower than 1500 Hz, with less than a 40 Hz difference between them, are presented to a listener dichotically (one through each ear).
For example, if a 530 Hz pure tone is presented to a subject’s right ear, while a 520 Hz pure tone is presented to the subject’s left ear, the listener will perceive the auditory illusion of a third tone, in addition to the two pure-tones presented to each ear. The third sound is called a binaural beat.
Wikipedia
I am using this free 30 minute “Earth Peace” track (via Aubrey Marcus). This track helps me relax and increases my chance of falling asleep.
Keep in mind that you need to set an alarm (for example for 15 or 30 minutes). Or else you might find yourself sleeping for 2 hours, disrupting your day and sleep schedule.