Thank you for the help! The code works, but now all I have to do is figure out how it works. 
Unfortunately, I have run into another snag. Some people have gone to bed and awoke on the same day and thus looking like they have slept for more than 24 hours.
Any suggestions on how to address this issue would also be appreciated.
Many thanks to any/all who help.
Jason
structure(list(bedtime = c("10:00", "11:00", "10:30", "11:00",
"10:00", "10:30", "11:30", "10:30", "10:30", "9:30", "10:30",
"8:30", "10:30", "12:00", "12:30", "10:30", "12:00", "10:00",
"11:00", "10:00"), bt.sleep = c("PM", "PM", "PM", "PM", "PM",
"PM", "PM", "PM", "PM", "PM", "PM", "PM", "PM", "AM", "AM", "PM",
"AM", "PM", "PM", "PM"), waketime = c("5:00", "6:30", "7:00",
"7:00", "7:30", "7:00", "7:00", "7:00", "6:00", "4:30", "7:30",
"4:30", "6:30", "8:00", "7:30", "7:00", "8:00", "6:30", "7:45",
"6:00"), wt.wake = c("AM", "AM", "AM", "AM", "AM", "AM", "AM",
"AM", "AM", "AM", "AM", "AM", "AM", "AM", "AM", "AM", "AM", "AM",
"AM", "AM"), Sleep = structure(c(1585796400, 1585800000, 1585798200,
1585800000, 1585796400, 1585798200, 1585801800, 1585798200, 1585798200,
1585794600, 1585798200, 1585791000, 1585798200, 1585717200, 1585719000,
1585798200, 1585717200, 1585796400, 1585800000, 1585796400), class = c("POSIXct",
"POSIXt"), tzone = ""), Wake = structure(c(1585821600, 1585827000,
1585828800, 1585828800, 1585830600, 1585828800, 1585828800, 1585828800,
1585825200, 1585819800, 1585830600, 1585819800, 1585827000, 1585832400,
1585830600, 1585828800, 1585832400, 1585827000, 1585831500, 1585825200
), class = c("POSIXct", "POSIXt")), `Time in bed` = structure(c(7,
7.5, 8.5, 8, 9.5, 8.5, 7.5, 8.5, 7.5, 7, 9, 8, 8, 32, 31, 8.5,
32, 8.5, 8.75, 8), class = "difftime", units = "hours")), row.names = c(NA,
20L), class = "data.frame")