Most organisms, including plants and animals, have an internal clock that helps them to cope with the daily, cyclical changes in the environment associated with periods of light and darkness. This internal clock is located in the suprachiasmatic nucleus (SCN) in the hypothalamus of the brain and is responsible for maintaining the rhythm of all other biological processes, including body temperature, feeding, hormone secretion, and immune function.

The SCN uses signals from the environment, such as day length, food availability and temperature, and adapts the circadian rhythm in response to these changes. Dysfunction of the endogenous circadian rhythms results in disturbances of sleep patterns, thus causing circadian rhythm sleep disorders. These disorders often present symptoms similar to insomnia or hypersomnia but are due to dysfunction of the circadian system.

Circadian rhythm sleep disorders include delayed phase sleep disorder (DPSD) and advanced phase sleep disorder (APSD). DPSD is characterized by late sleep onset and late waking time, whereas APSD is characterized by difficulty staying awake in the evening and waking up early in the morning. Unlike insomnia and hypersomnia, ASPD and DSPD are characterized by normal sleep quality.

Cocaine abuse can adversely affect brain pathways involved in maintaining circadian rhythms, thus disrupting the cyclicity of all biological processes, including sleep and wake patterns. Recent evidence indicates that there is a bidirectional relationship between cocaine use and circadian rhythms, with cocaine use influencing circadian rhythms and circadian rhythms modulating cocaine use.

How Cocaine Affects Circadian Rhythm Sleep Disorder?

Although studies have looked at the effect of substance abuse on sleep patterns, few have directly addressed the impact of substances like cocaine on the circadian clock. Cocaine, like many other substances of abuse, disrupts sleep patterns, indicating that it likely has an impact on circadian rhythms and thus CRSDs. Cocaine is a stimulant of the central nervous system that results in euphoric feelings, increased arousal and restlessness.

Consistent with these effects, cocaine intake often results in symptoms that resemble chronic insomnia. These symptoms include a longer duration or latency to fall asleep, a disruption of the sleep patterns and a decrease in the total sleep time. The disruption of sleep patterns includes suppression of rapid eye movement (REM) sleep. Deprivation of REM sleep is associated with cognitive deficits such as impaired memory, as well as mood disorders, including depression and anxiety.

Disturbances in sleep patterns persist even after withdrawal from cocaine use. Although the initial week of abstinence is marked by normalization of sleep patterns, sleep disturbances persist in subsequent weeks. Such disturbances include delayed latency to sleep, a decrease in total sleep time and an increase in REM sleep that is associated with excessive dreaming. Such changes in sleep quality during the abstinence period are considered to be partially responsible for setbacks occurring.

Cocaine may modulate circadian rhythms, driving the need for cocaine consumption at a certain time. Additionally, cocaine directly modulates the activity of the SCN by influencing its responses to various cues from the internal and external environment (light, physiological cues, food, etc.). This explains the ability of cocaine to disrupt sleep/wake cycles.

Can Cocaine Abuse Cause Circadian Rhythm Sleep Disorder?

It is difficult to determine whether cocaine abuse leads to circadian rhythm sleep disorders, or circadian rhythm sleep disorders lead to cocaine use. Although distinct from circadian rhythm sleep disorders, chronic cocaine users show higher rates of insomnia and hypersomnia, with hypersomnia being more prevalent in cocaine users. At the genetic level, the same genes that are expressed in the body’s master clock predispose an individual to cocaine addiction and CRSDs.

The SCN expresses two sets of genes that regulate each other’s expression in a push-pull manner, creating a 24-hour cycle. During a particular phase (for example, during the night), specific clock genes are upregulated, resulting in the downregulation of other clock genes.  During the daytime, the pattern reverses. Mutations in these genes influence the rewarding properties of cocaine, indicating their involvement in cocaine addiction.

Furthermore, these circadian genes are polymorphic. This phrase means that different variants occur for the same gene, with a slightly different DNA sequence resulting in expression of different traits. Certain variants of these circadian genes result in increased vulnerability to cocaine addiction, further highlighting the involvement of circadian genes in cocaine addiction. Polymorphism of the same circadian genes is also related to circadian rhythm sleep disorders, including advanced and delayed sleep phase syndromes.

Key Points: Cocaine and Circadian Rhythm Sleep Disorder

Keep the following key points in mind when considering cocaine and circadian rhythm sleep disorder:

  • Cocaine directly influences the master clock SCN
  • Cocaine use and withdrawal causes delayed sleep onset and disrupted sleep patterns
  • Genes involved in maintaining the circadian rhythm are involved in both cocaine addiction and CRSD
  • Simultaneous treatment for cocaine addiction and sleep disorders may be necessary since cocaine use disrupts sleep patterns and sleep disorders may result in cocaine intake to deal with the symptoms

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