How would sleep cycles work in a world with a years-long day?

This is in my world of balloons and zeppelins, war and peace, day and night. Sleeping may be the least important thing but it is still important. On this world, the day and night cycle is 8.89 of their years and 21 of our years. So I ask, how would sentient creatures in my world sleep? Below are some features I need in it.

1. They do need to sleep somehow so no alternative recharging
2. They cannot enter the night
3. They are sapient but do not use technology as the primary source of sleep (like space marines in war hammer 40k)

posted over 9 years ago

Uncle Tres‭

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