Sleep Restriction Therapy (SRT) is a component of Cognitive Behavioral Therapy (CBT). As such, it addresses certain aspects of insomnia. In the context of CBT, SRT teams up with other solutions such as Stimulus Control Therapy, which we have already discussed.
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SRT restricts time spent in bed and daytime sleep, intending to improve the quality of nighttime sleep. It aims to reshape patients’ sleeping habits. Restricting sleep is the most reliable method to increase the natural propensity for sleep.
Like other CBT components, SRT is well capable of addressing the problem of insomnia by itself. SRT impacts the early, middle, and late stages of sleep. It, therefore, presents a “complete” option for the treatment of insomnia.
On this page, we go into details about what SRT entails. More specifically we discuss:
- Sleep Restriction Therapy indications.
- Detailed description of SRT procedures. Examples.
- SRT variations.
- Resistance to Sleep Restriction.
- The science behind SRT.
Unlike with some other insomnia treatment methods, finding ideal candidates for SRT is a somewhat intricate exercise.
Therapists will require patients to compile a one-to-two week sleep log. Based on this data, patients will then determine their subjective sleep efficiency. The formula you can use to this end is:
The time you spend sleeping / the time you spend in bed x 100%
If you are a younger person and your score falls under 85 percent, your sleep efficiency is not satisfactory. The same is true if you are an older person and your score is below 80 percent. The good news is, if you fall into those two categories, SRT can likely help you.
There is another category of insomnia sufferers that is a good target for SRT. Patients belonging to this category do not report unsatisfactory sleep efficiency. When they are in bed, they do sleep. But they sleep way too little during the weekdays. They rise early, after about five hours of sleep and do not go back to sleep. On weekends, however, they repay some of the sleep debt they accumulate during the weekdays. They stay in bed long enough to fall back asleep and they then sleep in.
SRT is equally efficacious for various types of insomnia. No scientific research has identified it as being more suitable for one type than another. That means it will treat chronic insomnia, whether idiopathic or paradoxical insomnias.
Most CBT-based insomnia treatments carry very few, if any, contraindications. SRT is an exception in this regard. Given the fact that it can make patients very sleepy, it commands caution with several categories of patients.
Individuals whose work requires them to maintain vigilance, may thus not be good candidates for SRT. Initially, SRT will make most patients sleepy. Some of them may even fall asleep uncontrollably. Crane operators, truck drivers, long-distance bus drivers, air traffic controllers, and heavy machine operators should not undergo SRT. The risks of the therapy outweigh its benefits in their case.
There is a category of insomnia sufferers that includes patients who fall asleep quickly and sleep well, before they awaken for good, very early in the morning.
For such patients, SRT fails to deliver any of its usual benefits. It does not:
- Reduce sleep latency. Sleep latency in this patient category is already quite ideal as it is.
- Reduce the number, frequency, and duration of awakenings. As long as they are asleep, these patients sleep well.
- Increase the duration of sleep.
With such insomniacs, SRT tends to fall flat. There may be a sub-category within this group, however, that may warrant special consideration. Patients belonging to this sub-category stay in bed after they awaken. They say they just rest without sleeping. In some of these patients, something called “sleep-state misperception” may occur. This means that they do not realize they fall asleep for brief periods. Instead of resting while awake, they get some additional low-quality sleep. For such patients, SRT may retain some benefits.
Some insomniacs do not tolerate the side effects of SRT. These side effects are numerous and for some, they may be quite daunting. They include:
- Daytime sleepiness.
- Impairment of memory.
- Difficulties concentrating.
Insomniacs who cannot tolerate these side effects find it impossible to adhere to SRT. Thus, they will not get to enjoy the benefits of improved sleep depth and quality.
Initial SRT Procedures
SRT begins with a one-to-two week sleep diary. Patients undergoing therapy need to compile these reports. Based on this data, therapists can determine a handful of variables they need to initiate the therapy.
These variables are:
- Typical sleep duration.
- Wake-up time on workdays.
- The sleep-period where the best quality sleep occurs.
Specialists determine typical sleep duration by calculating the average based on total sleep times. Patients also provide a clinical interview before the therapy commences.
Once they have the needed variables, therapists set the starting TIB (Time in Bed) for patients, to the average sleep- duration. They will not set TIBs of less than five hours, however.
The wake-up time is the average workday wake-up time of the patient. Therapists are flexible in this regard since they need to consider the sleep period responsible for the best sleep quality of individual SRT patients.
If a patient logs his/her best sleep through the first two-thirds of the night, then the wake-up time may be set earlier than the average workday wake-up time.
Starting SRT Schedule Example
Based on the patient’s sleep log, the therapist has compiled the following information.
- Average bedtime to wakeup-time: from 11 PM to 6:30 AM.
- Average time in bed: 7.5 hours.
- Average time spent awake before falling asleep: 15 minutes.
- Average time spent sleeping per night: 5 hrs, 45 minutes.
- Average wakeup-time on workdays: 6:15 AM.
In his/her clinical report, the patient specifies that the latter couple of hours of his/her sleep are very light.
Based on this information, the therapist prescribes the following SRT schedule:
- The TIB is 5 hrs and 45 minutes. Since this is how much the patient effectively sleeps, this is how much time he/she should spend in bed.
- Given the sleep pattern of the individual, bedtime is kept at 11 PM.
- Per the mentioned variables, wakeup time is set to 4:45, every day, for a week.
Following a week’s therapy, the therapist re-assesses the patient. He/she then tweaks the SRT schedule as deemed necessary.
If in the above example, sleep latency were higher, and the sleep pattern allowed more quality sleep later in the sleep cycle, wakeup time could be tweaked to 6:15 AM. Bedtime might then be moved to 12:30 AM as well.
Middle-Phase SRT Procedures
As mentioned, the SRT schedule valid for the first week is merely the initiation phase of the therapy. Following the first week, the therapist re-assesses the patient and tweaks the schedule accordingly.
The immediate goal of SRT is to improve Sleep Efficiency (SE). Based on how this variable evolves, the therapist decides the following:
- If a young patient improves his/her SE to above 90 percent, the therapist will increase TIB by 15-30 minutes. Exactly how much the increase is within these limits, is something the therapist will decide on a case-by-case basis.
- The therapist takes similar action if an older patient’s SE improves to above 85 percent.
- If the SE of a young patient is between 85 percent and 90 percent, the initial SRT schedule remains valid. The same goes for older patients with SE between 80 percent and 85 percent.
- If the SE of a younger patient is below 85 percent, the therapist reduces TIB by 15-30 minutes. The same goes for older patients with SE below 80 percent.
Patients with paradoxical insomnia, who cannot tell how much they sleep, will not progress with SRT. The treatment method is therefore not suitable for them.
SRT Completion Procedures
The wrapping-up phase of SRT is an intricate exercise. Firstly, one needs to establish the end goal of the treatment. This goal cannot be the maximization of sleep efficiency. Sleep efficiency tends to be the highest when therapists limit TIB to five hours.
Not increasing TIB will yield exhausted patients ridden with a variety of other side effects, who are not able to function properly.
The therapy, therefore, aims to ensure restful sleep and proper daytime functioning. The net benefit of SRT is, therefore, defined as a cost/benefit ratio, where the cost is TIB and the benefit is proper daytime functioning.
Thus, the aim is to restrict TIB enough to ensure good sleep, but not as much as to negatively impact daytime functioning.
This point of maximum benefit/minimum cost is the one the patient should aim to maintain. He/she should focus on making this schedule a habit.
SRT Completion Procedure Example
During SRT, a patient has his TIB tweaked three times. Each time, he gains an additional 15 minutes in bed. Thus, his total TIB reaches the 7-hour mark. He goes to bed at 11 PM and wakes up at 6 AM.
Follow-up sleep logs register effective sleep times of 5 hours and 45 minutes on average. This translates to a SE of 80-85 percent. Given the age of the patient, this SE does not warrant additional TIB tweaks.
The patient also reports excellent daytime functioning.
This is the point where the therapist discontinues SRT, advising the patient to stick to the 11 PM – 6 AM sleep schedule.
The amount of consolidated sleep the patient gets is slightly increased compared to the pre-SRT baseline. Anxiety related to insomnia, and problems stemming from it, are eliminated.
SRT procedure modifications take aim at some of the critical points of the treatment. One such point is the introduction of the initial TIB period.
This period matches the effective sleep time of the patient. Still, some may experience it as serious sleep deprivation. Such patients experience significant daytime sleepiness, which may prevent them from functioning normally.
To circumvent such problems, some therapists will add 30 minutes to the patient-reported sleep time. This tweak makes the use of SRT possible with patients who would otherwise not be able to resort to it.
In some cases, sleep doctors my go as far as to allow patients some daytime napping-time.
Sleep compression is yet another twist to SRT. This method uses a gradual approach to reducing TIB, thus allowing patients to adapt on the go.
Some patients with paradoxical insomnia respond well to the increasing of TIB following the initial reduction. Therapists increase TIB for such patients regardless of the SE progress that they make.
Resistance to Sleep Restriction
There are always patients who will resist insomnia treatment one way or another. One such patient category finds it difficult to understand how getting even less sleep would help their insomnia. To address such concerns, therapists should:
- Explain circadian rhythms, sleep drive, and SRT rationale to patients.
- Inform patients that they will not limit their TIB to less than the time they spend effectively sleeping.
- Get patients to commit for at least a week.
- Explain the concept of sacrificing something short-term, for a substantial long-term gain.
Other patients will not understand why they cannot attempt to pay off their sleep debt after a bad night. With such patients, the therapist should insist that:
- Sleepiness will translate to better sleep next night.
- Patients have control over when they go to bed and when they get up. They are mostly unable to willingly fall asleep though.
- If the sleepiness of the patient carries hazards to others, they should be allowed some nap time.
- Patients should avoid caffeine as a solution to their plight.
A different class of patients will simply state that they are unable to stay up until their designated bedtimes. The doctor should advise such patients to:
- Avoid lying down.
- Avoid activities that make them sleepy.
- Do something stimulating instead.
- Try to change their mindset. Tell themselves that they are indeed capable of staying up.
The Science Behind SRT
Most scientific studies assessing the efficacy of SRT looked at it in the context of Cognitive Behavioral Therapy. There is a handful, however, which focused solely on SRT.
In a 1987 study, Spielman AJ, Saskin P, and Thorpy MJ focused on the treatment of chronic insomnia through SRT. 35 people participated in the study. 23 of them returned for a follow-up assessment. Researchers concluded that SRT is indeed an effective treatment for most forms of chronic insomnia.
In a 1995 study, Riedel BW, Lichstein KL, and Dwyer WO looked specifically at the sleep compression variant of SRT. They found that the therapy was highly effective, especially when coupled with therapist guidance.