I could not get my Latitude 5515 to sleep properly after weeks of playing with it. I settled on a song and dance of setting hibernate on and making sure I pull

I could not get my Latitude 5515 to sleep properly after weeks of playing with it. I settled on a song and dance of setting hibernate on and making sure I pull the power cord out and wait a few seconds before closing the laptop. Works every time and 'bootup' takes a few seconds.