Sounds about right, although there are theories that humans were actually designed to sleep in smaller segments spaced out throughout a 24 hour period, usually consisting of one to three cycles per sleep segment, as it is said that this is how early humans slept before the creation of industrial societies and electricity.
I actually sleep this way about half of the week due to my work schedule. On the the three days I have to wake up early I usually sleep for three cycles, and then sleep for another one or two cycles about 5 hours later. Although I am usually pretty tired for the initial waking period, I feel fully rested after the second sleep segment. This sleep schedule is also extremely beneficial for inducing lucid dreams and out of body experiences, for at the end of the second segment one's body and mind are naturally in the ideal conditions and it is a nearly effortless process. With proper intention and technique these experiences are almost guaranteed at the end of the second segment.
Dreams normally occur at the end of each sleep cycle for the average person, so awaking after a dream is an indicator that a full cycle of sleep has just been completed. This may help if you are interested in keeping track of your sleep cycles.