Real-Life Math -- Solution
How many EPOCHs were recorded between Time Zero and lights on?
From
10 p.m. to 7 a.m. is 9 hours.
1 minute = 2 EPOCHs
60 minutes per hour
x 2 EPOCHs per minute = 120 EPOCHs per hour
9 hours x 120 EPOCHs per hour
= 1,080 EPOCHs
Using EPOCHs, what is your patient's sleep
efficiency?
Time Zero to falling asleep = 75 minutes
75
x 2 = 150 EPOCHs
Nighttime awake period = 21 minutes
21 x 2 = 42
EPOCHs
Time from morning wakeup until lights on = 80 minutes
80
x 2 = 160 EPOCHs
Total time awake: 150 + 42 + 160 = 352 EPOCHs
Total
sleep time: 1,080 - 352 = 728 EPOCHs
Sleep efficiency: 728 / 1,080 x
100 = 67 percent
The patient's sleep efficiency is 67 percent.
Ninety percent would be considered normal.
"We are always talking about
how many hours somebody slept to the closest 30 seconds, how much time they
spent in certain stages of sleep, what their sleep efficiency is," said Laree
Fordyce, a polysomnography technician. "In many clinics, the computer calculates
the numbers, but not in all clinics."