Circadian rhythms, sleep and exercise

A cure for insomnia?

Do you have trouble getting to sleep at night or staying asleep? About 30% of the adult population reports difficulties initiating sleep, sustaining sleep, or experiencing restful sleep. To deal with these problems, many people resort to medications or some form of supplement. But it now appears that there is an effective way to banish insomnia without the use of chemicals, by simply applying the principles of hormesis.


The remedy I want to discuss here is called Sleep Restriction Therapy (SRT). I credit Derek Haswell for bringing SRT to my attention. A 4-8 week course of treatment has been shown to be very effective in restoring normal sleep. The basic idea behind SRT is to limit your sleeping in a controlled manner until it renormalizes. As with any application of hormesis, the solution may at first seem paradoxical: to combat a stress you should apply judicious amounts of that very stress to train the mind or body to adapt. It works for building muscles, improving eyesight, normalizing appetite, and improving immunity. And sleep therapists have now found a way to use hormesis to improve the quality of sleep.

The protocol. Here is how Sleep Restriction Therapy works:

Determine a fixed time to wake up every morning and set your alarm for that time. This is an absolute requirement: when the alarm goes off you must get out of bed immediately with no snoozing or exceptions. If necessary, use a loud alarm and put it across the room. Some researchers find that exposure to bright morning light upon waking is important to the success of SRT.
Determine the minimum number of hours you need to sleep. This is usually done by keeping a sleep log for several nights to figure out the average number of hours you are actually sleeping. If you are in bed for 8 hours but are awake for 2 of those hours, then your sleep requirement is 6 hours. In general, the minimum sleep requirment should never be less than 4.5 hours.
Do not go to bed or even go into your bedroom until the official bedtime. If your wake time is 6 a.m. and your initial sleep time is five hours, that means you cannot go into your bedroom to sleep until 1 a.m. You have to keep yourself awake between 6 a.m. and 1 a..m. the next day. No napping, lying down or nodding off is allowed. This is difficult and can produce drowsiness and grumpiness during the initial days of treatment. In some versions of SRT, slightly longer hours are allowed on weekends as a “reward” for making progress.

Measure your “sleep efficiency” each night. Calculate sleep efficiency as the hours you actually sleep expressed as a percentage of the total hours you are in the bedroom. To track sleep efficiency, keep a sleep log — a record of when you go to bed and wake up during the night, noting the related circumstances and activities. Your goal is 90% or better sleep efficiency. An alternative method is to use a home sleep monitor such as that made by Zeo. The Zeo sleep monitor is an affordable and comfortble “headband” that wirelessly transmits data on your different sleep phases and sleep efficiency to a bedside “alarm clock”, with the ability to view your progress on your PC. I’ve found the Zeo to be very useful in analyzing sleep patterns. It reveals the inner workings of your sleep in a way that a manual sleep log cannot.
Adjust your sleep time. If your sleep efficiency is greater than 90%, increase your sleep time by moving your bedtime 15 minutes earlier. If your sleep time is less than 85%, delay your bedtime by 15 minutes.
Allow your sleep to normalize. Continue the treatment until your sleep time can be increased to ”normal” sleep time of 6-8 hours with at least 90% sleep efficiency and subjective feeling of restfulness upon waking and during the day.
Case study. Here is a very compelling video about the success that one British man had using SRT to overcome insomnia:


A study of SRT in 10 elderly patients found that it significantly reduced both sleep latency (time to fall asleep) and subsequent waking during sleep. And the benefits were still in place 3 months after ending the therapy. SRT appears to be effective for most types of insomnia, except for sleep disturbances related to depression, bipolar disorder, sleep apnea or circardian disorders resulting from, e.g., shift work. One of the immediate benefits that patients note is the reduction of “anticipatory anxiety” — the time and concern spent worrying about what the night will bring. Many insomniacs see their bedroom as a prison or place of dread. SRT very quickly compartmentalizes that anxiety. Once they begin to bank 5 or 6 good hours of sleep each night, the progress itself helps to dissipate the anxiety, which in turn tends to make for better sleep.

As with any application of hormetic stress, SRT at first involves “one step backward” by seeming to make things worse. And indeed the first few days may bring increased drowsiness, while the benefits take weeks to become evident. The reality is that our bodies adapt often slowly, over a period of weeks or longer. And so it is with SRT. But once patients begin to adapt to the new sleep regimen, the quality of their sleep usually improves markedly. Several weeks of drowsiness and irritability seems a small price to pay for a cure that lasts.

Why does it work? Looked at from a behaviorist perspective, SRT is a form of behavior modification based upon stimulus control. Because patients are truly much more tired when they are finally allowed to climb into bed, the association between the action of getting into bed and the response of falling asleep is strengthened, and the association with “tossing and turning” is weakened. Undoubtedly, at the level of neuropeptides and receptors in the hypothalamus, SRT must be restoring a functional homeostasis. The neuronal pathways, transmitters, and receptors involved in sleep regulation are quite complex. The ascending arousal system located in hypothalamus interacts with sleep-active neurons in the ventrolateral preoptic nucleus (VLPO) producing a “flip-flop switch” that produces distinct sleep-wake states with abrupt transitions. The sleep disruptions characteristic of insomnia are believed to involve an excess of corticotropin-releasing factor (CRF) secreted by the hypothalamic-pituitary-adrenal (HPA) axis. This results in excess production of the hormones ACTH and cortisol, leading to hyperarousal. It appears that Sleep Restriction Therapy quiets the HPA, leading to improved sleep.

Regardless of the underlying mechanism, Sleep Restriction Therapy appears to be an excellent example of hormesis, a chemical-free way to teach your body to adapt, by exposing it to controlled doses of the very same stress than you want to tolerate more effectively.