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Did you know that your body has a sleep drive that builds over the course of the day? Just as feelings of hunger increase over time and gradually signal to you that it’s time to eat, your sleep drive builds over the course of the day, letting your body know it’s time for rest.
The easiest time for you to fall asleep is when your sleep drive is at its highest point. From this, we can learn that if you are trying to fall asleep when you’re not tired, you will likely experience frustration — which, in turn, makes it harder to fall asleep.
We can help our bodies know internally that it’s time to go to sleep by intentionally building sleep drive over the course of the day.
The fastest way to use your sleep drive to fall asleep at bedtime is to set a consistent wake time and stick to it. Don’t let yourself nap, despite the temptation. The wake time should also be the same on weekdays and weekends. Anticipate that the first few days of a consistent wake time will involve some discomfort and less sleep than usual, overall. We call this sleep restriction, and it is a temporary practice intended to act as a reset. (Please note, we never endorse restricting your sleep to less than five hours per night!) You can think of this period of sleep restriction as being similar to traveling across timezones. After a few days your body starts to adjust and knows when it’s time for bed.
It might seem counterintuitive, but a small, temporary increase in sleepiness can help improve your sleep in the longer term.
⚠️ Warning: Restricting overall sleep is only for people with reasonably predictable nighttime schedules. If you are often awake during the night to provide care to children or babies (including waking to feed, nurse, or otherwise attend to infants), then please do not participate in this exercise. And for goodness’ sakes, take all the naps you can possibly get.
So, we know that setting a consistent time can help with sleep onset, that is, falling asleep when you want to be asleep. But what about quality of sleep? That is, do you feel adequately rested upon waking? This is where Sleep Efficiency comes in.
To help convey this concept, let’s return to that hunger and eating analogy: How would you feel if you snacked all day on tasty, but non-nourishing treats, and then were offered a beautiful, healthful and nutrient-dense meal? You probably wouldn’t be very hungry. If you did force yourself to eat (because you thought the meal would nourish your body), it wouldn’t feel great.
The same is true with sleep. Little bits of sleep throughout the day, hanging out in bed, or “trying” to fall asleep make the sleep you do get feel less restorative. Getting a good night’s sleep and waking feeling refreshed is a subjective experience, and only you can evaluate whether you find your sleep restorative. Sleep efficiency is an objective measure of your sleep, and is correlated with perception of good sleep. The exciting news here is we can measure your sleep efficiency and take active steps to improve it, if needed.
Sleep efficiency is the ratio of how much time you spend in bed vs. how much time you’re actually sleeping.
For example, if every time your head touched the pillow, you fell asleep instantaneously, and when you woke in the morning, you sprung right out of bed, you’d have perfect sleep efficiency of 100%.
Now, no one has a perfect score of 100%, but higher scores are better than lower scores.
A sleep efficiency of 85% or higher is considered healthful. Anything less than 85% suggests you would benefit by doing some exercises to increase your sleep efficiency.
To calculate your sleep efficiency, we take the average amount of time you spend sleeping and divide that by the average amount of time you spend in bed.
Download the Sleep Efficiency Worksheet (PDF) for easy guidance on working this out.
The worksheet will also help you get a sense of patterns in your sleep habits, like different amounts of sleep on different nights, and changes in bed times and wake times.
Starting with the “in bed” column, place an “x” during any hour period that you spent in bed in the previous 24 hours. Now, move to the “sleeping” column and do the same thing.
If you track this every day for a week, you will start to get a clear sense of when you’re sleeping and when you’re awake. You will also be able to calculate averages for both “in bed” and “asleep.”
Finally, calculate your sleep efficiency score by dividing “asleep” by “in bed.”