"on days off" is a perfectly correct and usable phrase in written English.
For example, you could say "I like to spend my days off relaxing at home".
Longer sleep duration on days off was associated with the combined effect of one allele of the rare variant in MTNR1B.1 and heterozygosity at the PER3.6 locus.
And on days off, I make salads and pretend they're good for me.
On days off on the road, James and Jent would normally work out twice a day.
But on days off, he was an historian, researching the island's past.
On days off, explore the sea caves and cliffs or visit nearby vineyards.
Three strategies distinguished those who switched completely from nights to days on days-off.
Subjects also reported number of minutes needed to get out of bed after waking up on days-off.
Several studies have indicated that the sleep/wake patterns of simulated shift workers on days-off can significantly affect night-shift performance [34], [35], [36], [37].
The MTNR1B.1 SNP in MTNR1B and the PER3.6 polymorphism in PER3 interacted to predict sleep duration on days-off for those that work day-shift.
Interestingly, ∼86% of larks chose to switch back to nocturnal sleep on days-off, and just over 1/3 of them chose the "No Sleep" strategy.
