Sleep Continuity/Efficiency
It is perfectly normal to take up to 30 minutes to fall asleep and to wake up during the night. In fact, falling asleep too quickly and sleeping the whole night through can sometimes be a sign that something is not quite right.
What is Sleep Efficiency?
Sleep efficiency is the amount of time that you are sleeping while you're in bed
Sleep efficiency = Average time asleep ÷ Average time in bed
If you wanted to calculate this, you would divide the time you were asleep (e.g., 6 hours and 30 minutes) by the number of hours you were in bed (e.g., 8 hours and 30 minutes). Dividing 6.5 by 8.5 is a sleep efficiency of around 76%. So what does 76% efficiency mean? Sleep efficiency can be somewhere between 100% efficiency, which means you were never awake at all while in bed, to 0% efficiency, which means you were never asleep for a moment that you were in bed. The idea that you are dividing the time you were asleep by the time you were in bed, implies that that we expect that it's not going to be 100%. This means that we might expect that some wakefulness is a part of sleep, which is true.
What factors can influence this sleep dimension?
Sleep drive: the more time you are out of bed and active, the stronger your drive for deep sleep. A strong drive for deep sleep makes it more likely that you will fall asleep more quickly and any awakenings will be brief.
Time in bed: too much time in bed will decrease efficiency (e.g., insomnia) and too little time will increase efficiency (e.g., sleep deprivation)
Medical/Sleep disorders: some disorders, such as sleep apnea for example, can produce disruptions in your sleep until most of the time you are in bed you are sleeping but with very fragmented, poor quality sleep.
Consequence of an unhealthy sleep efficiency
Overly efficient sleep is suggestive of fragmented sleep and sleepiness. Daytime sleepiness can result in falling asleep while driving and can negatively impact quality of life.
Inefficient sleep is most often associated with insomnia and when untreated, insomnia predicts the development of mental disorders and negatively impacts quality of life.
What is healthy sleep efficiency?
It is normal to be awake up to 30 minutes throughout the night. It is normal to take about 10-30 minutes to fall asleep.
On average, a healthy sleep efficiency is to be asleep about 85 to 90% of the time that you are in bed.
Sleeping above 90% of the time you are in bed on average is too high.
Sleeping less than 85% of the time you are in bed on average is too low.
Recommendations for efficient sleep
Generally speaking, your time in bed should closely match how much sleep you produce on average.
If your sleep efficiency is too high (on average greater than 90%), extend your time in bed by 30 minutes for a week and see if you feel better and your sleep efficiency is closer to 85-90%. If extending your time in bed does not decrease your sleep efficiency below 90%, speak to your doctor. You may need an overnight sleep study to determine if there is a sleep disorder.
Build a strong drive for sleep by being physically active during the day.
If your sleep efficiency is too low (on average less than 85%), decrease your time in bed to more closely match your average sleep time. Do not set your time in bed below 6 hours. If at the end of two weeks, your sleep efficiency remains low, you should seek out a treatment called Cognitive Behavioural Therapy for Insomnia. For more information visit: https://www.researchsleep.ca/insomnia
Challenge the belief that you should be asleep 100% of the time that you are in bed. Firmly believing that we should “sleep through the night and not wake up until morning” can create problems. If something wakes you up, or if you have to get up to go to the bathroom, you're more likely to be upset. Being upset can turn short awakenings into longer ones. Remember, it's perfectly normal to wake up at night!