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Trying to quit smoking or reduce your alcohol intake? One of the biggest hurdles to quitting a habit or overcoming an addiction is managing the cravings.

Craving of anything, from sugar to nicotine or alcohol, or harder drugs like cocaine and heroine, is often triggered by something in the environment. For smoking it may be seeing someone light up, or, for alcohol, entering the local bar.

I’m going to talk about a recent study that looked at the neuroscience behind how improved sleep quality, not just sleep hours, aids your ability to maintain your decision to kick a habit or an addiction by controlling the craving blueprint in the brain after quitting.

Good quality sleep is a must for optimum mental health. As I sit here pondering over this blog post I overheard the words “I’m tired. I didn’t sleep well”. If you find yourself waking up feeling groggy even with sleeping for the recommended number of hours, then you, like estimated one-third of adults, are probably not getting enough good quality sleep. Sleep that is fragmented or broken up by many awakenings, often without the sleepers’ knowledge, did not consist of enough restorative, or REM/ dream, sleep.

Restorative sleep is important for brain health and functions like moving memories from short-term to long-term storage. Let’s talk more about how improving your sleep quality could help your good intentions of trying to break that bad habit.

Sleep manipulates your cravings

The intensity of craving for something you are trying to quit increases during the first few days and can be lingering, even months after quitting. This is known as craving incubation. In humans it is thought that sleep disruption, like sleep that is fragmented, may make an addict more vulnerable to relapse.

I am going to summarize a recent study in the Journal of Neuroscience conducted in the labs of Yan Dong and Yanhua H. Huang led by Bo Chen and Yao Wang at the University of Pittsburgh, Pittsburgh, Pennsylvania, USA., that examined how sleep quality is affected by cocaine addiction and withdrawal; and how manipulating sleep architecture can help with cravings and molecular blueprints of addiction in the brain.

According to the Foundation for a Drug-Free World, cocaine is the second most widely used and trafficked illegal recreational drug in the world. The World Health Organization website claims that “cocaine dependence has become a substantial public health problem, resulting in a significant number of medical, psychological and social problems, including the spread of infectious diseases (e.g. AIDS, hepatitis and tuberculosis), crime, violence and neonatal drug exposure.”

Similar to the rate in humans, about one fifth of rats exposed to cocaine will become addicted.

Sleep can be measured in the brain with wires that sit on the scalp. Different stages of sleep have a signature electrophysiology pattern, or oscillation, that helps researchers and doctors measure different features of sleep including quality (see previous blog here). In this study the researchers measured sleep in rats for three days before cocaine exposure.

The rats were then placed in a chamber where they could choose to get cocaine by poking their nose into a hole that either contained cocaine or nothing. The cocaine was administered automatically via a cannula if they poked their nose in the correct hole. They were given the opportunity to take cocaine for five consecutive days and rats that poked for cocaine over a certain amount of times were deemed “addicted”.

The sleep of the addicted rats was then assessed five days after cocaine withdrawal and again at three weeks. The researchers found that the rats had sleep problems that consisted of less total time sleeping, more frequent transitions between awake and sleep states, and less time spent in restorative/ REM sleep. These changes were persistent even three weeks after cocaine withdrawal. Thus, the addicted rats that were going through withdrawal had poor quality or fragmented sleep.

Rats are nocturnal so they sleep during the day (light cycle) and are active at night (dark cycle). The researchers wanted to see if they could improve the quality of the sleep by manipulating the sleep patterns of the rats. By eliminating the amount of time the rats spent “napping” during the dark cycle they were able to increase the amount of time the rats spent in restorative/ REM sleep during the light cycle. The equivalent in human would be that when day naps are eliminated, the quality of sleep at night is improved. Avoiding naps is often prescribed to those suffering from insomnia.

Manipulating sleep can help or hinder an addict through withdrawal

The sleep disruption during withdrawal enhanced the rats craving incubation. The number of times they poked their nose in the hole to get their cocaine fix was increased when they re-visited the chamber (this will activate environmental cues for the addiction, just like seeing your favorite bar). The longer the period of sleep disruption, the more likely they were to seek cocaine.

The researchers wanted to understand better what components of sleep affected the ability of the rats to control cocaine cravings during the withdrawal period.

In addicted rats, the researchers found that restricting the number of “naps” could improve “night” REM sleep. Better quality sleep led to a reduction in craving incubation (the rats were less likely to nose poke for cocaine) that was correlated with the number of days that sleep quality was improved. On the other hand, waking up the rats to increase sleep fragmentation led to more cocaine seeking and worsened craving incubation.

In other words, better quality sleep aids ability to manage cravings. The better the sleep, the more successful you will be at resisting the urge.

Craving blueprint in the brain

Why does fragmented sleep affect your brain’s ability to manage your cravings? That is what the researchers looked at next. A type of receptor, called CP-AMPARs that detects a brain chemical called glutamate, is thought to be the molecular blueprint of cocaine craving incubation.

During a long withdrawal from cocaine CP-AMPARs are increased in the nucleus accumbens. The nucleus accumbens is involved in the emotional reward system, playing a role in feelings of pleasure and in motivation. Cocaine, like other addictions, hijacks the brains natural reward system. Cocaine prevents dopamine from being cleared away after it is released, meaning there is more dopamine around, especially in the nucleus accumbens.

Taking brain slices from the addicted rats, the researchers were able to record electrical activity from individual brain cells using a technique called “whole-cell patch clamp”. The researchers measured electric currents from the brain cells in the nucleus accumbens. When the rats were in withdrawal they found increased amounts of current in the brain cells produced through activity of these craving incubation receptors, promoting craving for cocaine. This increase was eliminated in the rats that were on the nap-restricted regime.

This suggests that fragmented sleep leads to a build-up of receptors in the brain that make it harder for you to resist a craving and encourage you to seek out your addiction.

Concluding remarks

This study suggests that sleep is an integral part of not only the manifestation of addiction but also an integral part of recovery from addiction. Poor quality sleep can increase the molecular blueprint of cravings in the brain, making it harder for you to stick to quitting, even months after your last fix. Unfortunately it may not help with your sugar cravings as the researchers found no affect on sleep and sugar intake.

Anyone with sleep disturbance (stress, new baby, chronic pain, insomnia etc.) knows that a night of multiple awakenings, even if the total number of hours “asleep” are as recommended, can leave you groggy and less than refreshed the next day. When this sleep disturbance manifests in people with mental illness, or Parkinson’s Disease and dementia, it can exacerbate symptoms. It also raises questions about mothers who successfully give up their addictions (like smoking) while pregnant only to succumb to their addictions during those tiresome newborn stages. Improving sleep quality in all these affected populations can improve relapse outcomes.

The good news is, if the results of this study hold true to humans, helping your brain to stave off your cravings during the difficult withdrawal process may be as simple as improving the quality of your sleep. Experts claim that you can improve sleep quality through restricting day time naps (no more than a power nap), better diet, restricted bed and wake times, more day activity and exercise.

So, if you want to stick to your New Year’s resolution to quit smoking, stop that drug taking or reduce your alcohol intake... then time to focus on your sleeping habits.

To view the original paper discussed in this blog “Sleep Regulates Incubation of Cocaine Craving.” in The Journal of Neuroscience please click here.

Cocaine addiction links:

http://www.drugabuse.gov/publications/research-reports/cocaine/
http://www.nhs.uk/Livewell/drugs/Pages/drugs-recovery.aspx
http://www.drugfreeworld.org/drugfacts/cocaine/international-statistics.html
http://www.who.int/substance_abuse/facts/cocaine/en/

The Blog was written by Carolyn Lacey, Scientific Outreach Manager at Neurexpert. To learn more about Carolyn and Neurexpert, please click here.