What is sleep restriction? How does spending less time in bed help with sleep?
When people have trouble either getting to sleep or staying asleep, they often go to bed earlier or lay in bed later allowing more time for sleep. But, this doesn’t result in more sleep, just more time in bed awake, wishing for sleep and can make sleep problems worse rather than better. The principle of sleep restriction is matching the amount of time spent in bed to amount of sleep people are actually getting, rather than the amount of sleep they wish they could get. This minimises the amount of time spent awake in bed, which is important, as time awake in bed is often time spent getting frustrated about not sleeping and developing poor sleep habits like using smartphones or laptops in bed. Over time, people gradually find they are sleeping longer and can lengthen the amount of time they spend in bed.
Does sleep restriction work?
The short answer is yes. Sleep restriction is a very powerful tool to help reduce insomnia, making it easier to get to sleep or get back to sleep during the night. Recent research done by University of Auckland researchers, including psychiatrist, Dr Tony Fernando, showed improved sleep quality reduced symptoms of insomnia, shorter time taken to get to sleep (sleep latency) and less time awake during the night (wake after sleep onset – WASO).
You can hear an interview with Dr Fernando describing his research and how he uses sleep restriction with patients as part of this podcast on cognitive behavioural therapy for insomnia (Dr Fernando’s interview is from 30:39 to 38:28).
Although sleep restriction is a helpful strategy, it works best when used as part of cognitive behavioural therapy for insomnia (CBT-I). There are 5 core components to CBT-I; sleep restriction, stimulus control, relaxation strategies, cognitive therapy and sleep hygiene measures. A meta-analysis (summary of all data published) of the effectiveness of CBT-I, When these 5 components are combined, published in the Annals of Internal Medicine showed that on average people went to sleep 19 minutes faster and stayed asleep 26 minutes longer after CBTi.
How do I do sleep restriction?
When starting sleep restriction it’s important to understand that initially you may be more tired or sleepy than you have been. It’s not uncommon for sleep to get a little worse for the first 3-4 days, before it begins to improve. So, don’t start sleep restriction unless you are ready to commit to it and persist with the changes to your sleep pattern.
The starting point for developing your sleep restriction program is to record how much sleep you are actually getting as well as how much time you are spending in bed. This is best done using a simple sleep diary. I like visual sleep diaries as they allow you to look at your sleep pattern which in itself can provide insights in to your sleep.
You can download a visual sleep diary here.
Once you’ve collected at least 1 week of sleep diary data you can figure out how many hours to spend in bed. Looking at your sleep diaries, calculate the average amount of sleep each night, by adding up the total number of hours of sleep on all night and dividing that number by the number of days. In the diary example below, there were 38 hours of sleep over 7 days, giving an average of 5.4 hours of sleep per night. Add 30 minutes to your average amount of sleep per night, to find out how long you are able to spend in bed each night.
The next step is to chose a consistent wake-up time. Now that you know how much time you can spend in bed each night, choose a time that would suit you to get up each day. You’ll need to bear in mind that this is likely to be earlier than you are used to, particularly if you are going to be spending much less time in bed that you have been.
Once you’ve chosen your wake-up time, then determine the earliest time you are able to go to bed. You calculate this by counting back from your wake up time. For example, from the diary above, where the average sleep per night was 5.4 hours, the time allowed in bed would be 5.9 or close enough to 6 hours. So, if a wake-up time of 6:30am was chosen, the earliest time to go to bed would be 12:30am. The aim is for you not to go to bed until you feel sleepy, and even if you are sleepy, not before your designated time.
Once you start following your new schedule, keep filling in your sleep diary, as you’ll use this each week to revise your sleep times. As the example below shows, with a line indicating the time of getting in to bed at 12:30am, it takes a few days before the time taken to get to sleep shortens and there is less time awake during the night. But towards the end of the first week, particularly nights 4-5 (Thursday and Friday) sleep has improved.
At the end of the first week of your new schedule, use your sleep diary to calculate your sleep efficiency. This is the proportion of the time you spend in bed that you are asleep. This is normally between 80-85%. You calculate the sleep efficiency by dividing the number of hours of sleep by the number of hours you spend in bed. In the example above, there are 34.5 hours of sleep and 44 hours in bed for the week, giving a sleep efficiency of 78%.
Based on your sleep efficiency calculation, use the guide below to adjust the time you are allowed in bed each night each week:
- If your average sleep efficiency is > 85% and you feel that you are not getting a sufficient amount of sleep for optimal functioning during the daytime, increase your allowed Time in Bed by 15-minutes, at either end of the night.
- If your sleep efficiency is < 80%, decrease your Time in Bed by 15 minutes, at either end of the night. However, you should not stay in bed less than 5.5 hours.
- If your average sleep efficiency is between 80% and 85% continue on your current schedule
How long should I stay on sleep restriction?
It’s hard to stay on a strict sleep restriction schedule over months, so for most people, I’ll use sleep restriction as outlined above to get their sleep on track. But once they feel that they are sleeping better will relax things, stopping completing sleep diaries and being less strict about times of going to bed or getting up in the morning.
But, it’s important to maintain the general principles of sleep restriction, that is:
- Matching the amount of time you spend in bed to the amount of sleep you are actually getting
- Avoid slipping back in to the pattern of being in bed for the amount of time you wish you were sleeping
Sleep restriction is also a good tool to use if symptoms of poor sleep or insomnia come back. Going back to a more strict sleep restriction routine for a few weeks is a very helpful strategy to get sleep back on track.
Related posts & links:
- New York magazine article on sleep restriction
- Cognitive behavioural therapy for insomnia
- Plan to manage insomnia
- Sleep hygiene
- Stimulus control
Need more information about how you can sleep better?
At Sleephub we understand the struggle people endure with sleeping problems which is why we have created a comprehensive FAQs page with information for those seeking information about sleep disorders and potential solutions.