You hear this term and automatically think, 100% must be what I'm shooting for! That's not the case with sleep efficiency, which is the ratio of total time spent asleep to the total amount of time spent in bed. If your sleep efficiency is too high, you might be constraining your child's sleep window -- try putting them to bed earlier and see what happens over the course of a few days -- they may actually need more sleep than you think. If their sleep quality is too low, your child may be spending too much time awake in their bed, or having extra long wake-ups during the night.
Take a look at things like their electronics time before bed, which can create over stimulation. Or ask yourself, are they doing too much in bed and they no longer see it as a place for sleep, but a place for everything else? In your assessment report this area will be addressed with more detail based on your child's actual results.
Less than 85% sleep efficiency
Your child is spending too much time awake in bed
Your child’s bed may no longer be a cue for sleep
Your child maybe having trouble falling asleep or experiencing extra long wake-ups at night
90% to 95% sleep efficiency
98% or higher sleep efficiency
Your child may need more sleep but their sleep window is too constrained
Your child might be having very early wakeup times (defined by school schedules, etc.)