Until today, the attacks came in three- to four-hour intervals.

Michael is taking AZT at four-hour intervals in this volume.

Consequently, heroin must be used several times a day at about four-hour intervals, to prevent withdrawal.

But we weren't all on the same clock-crew and passengers had our clocks staggered at four-hour intervals.

Lee, you'll be relatively stationary while the rest of us are moving around, so the others will call in to you at four-hour intervals.

Mingle freely with the other medical personnel, do exactly what's expected of me, and try to report in to you at four-hour intervals.

What he wanted was ten days of unconsciousness, broken only by huge meals at four-hour intervals.

"Just make sure you don't run into our Jeek friend at one of these four-hour intervals."

We will take fatigue shots in three hours and at four-hour intervals until we've cleared the Arctic Circle.

He'd given Roland three vials of fluid, to be taken at four-hour intervals, beginning well before the lethargy began to steal over him.