There are 3 books in the Dayworld series. The newest book is Dayworld Breakup which came out in 1990.

1
Dayworld

Book cover of Dayworld
In the year 3000 a remedy has been found for the world's overpopulation. For six days out of seven, everyone is kept in hibernation; on the 7th day they emerge - to live for a day. In this way the world can support a population whose one-day-a-week lives span hundreds…
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2
Dayworld Rebel

Dayworld Rebel
Jefferson Caird joins an outlaw band of daybreakers and uncovers the layers of deception that world government has inflicted on the people it has sworn to protect

3
Dayworld Breakup

Dayworld Breakup
Tor: 1990. First edition. Third novel in the trilogy, which also includes "Dayworld" (1985) and "Dayworld Rebel" (1987).