I used Audacity to generate files of silence in lengths of 1, 3 and 5 minutes.
I add them in a few of each as needed to pad out enough silence.
For sleep, I put half hour between subs as they’re an hour-long (90-minute sleep cycle and all). This seems to affect my sleep less than if I just have them playing all night.
During the day, if I do it this way, it depends on how long I’ll be listening. and how long I’m in the office.
if it’s my typical 10-hour workday, and I have 5 subs to listen to, then I add in 5 hours worth of silence. Usually for that I’ll shuffle the entire thing then, so that by the time 10 hours is up, I’ll have been through the whole thing buy my brain can’t figure out the timing to be able to block or stonewall as much due to acclimation.