This study examined the relationship between sleep and gambling severity in a sample of non-treatment seeking gamblers. These results indicate that decreased sleep quality is seen in any form of gambling disorder (problem or pathological), but only pathological gamblers experience significantly increased daytime sleepiness relative to recreation gambling controls. Although a few studies have made note of sleep disturbances experienced during crisis or withdrawal,55,56,59
these findings demonstrate that problematic sleep occurs for current non-treatment seeking gamblers as well.
Although an increasing trend in ESS scores based on gambling severity is visually evident (), a statistically significant difference was not found between recreational and problem gamblers. However, it should be noted that although no statistically significant difference was found in mean daytime sleepiness between recreational and problem gamblers (P
= .065), these results indicate a high likelihood that a difference does exist in mean daytime sleepiness between these groups. A larger sample size may have allowed the achievement of statistical significance. This implies that each categorical increase in gambling severity may correlate with a corresponding increase in mean ESS score, and that a hierarchical relationship between recreational, problem, and pathological gamblers likely does exist in terms of daytime sleepiness. However, in terms of the PSQI, no difference was found in sleep quality between problem and pathological gamblers (P
= .843), implying that any form of disordered gambling is sufficient to induce significantly decreased sleep quality. Studies have demonstrated that the PSQI and ESS measure different components of problematic sleep.72
Surprisingly, a statistical difference was not found for the hours of sleep per night and the time it took to fall asleep between the three gambling groups. Because significant differences were found on the ESS and PSQI, this may indicate that gamblers acquire some sleep problems but not others as gambling disorders progress.
Gamblers may have trouble with sleep for a variety of reasons. It is suspected that social, psychological, and biological factors all play a role in promoting disturbed sleep for the gambling population. Socially, gambling is highly accessible due to the continuous availability of casinos and online gambling (24 hours a day, every day of the year). In addition, disordered gamblers may experience dissociation when gambling and lose track of time.74,75
The combination of possible dissociation and accessibility to gambling creates a setting conducive to gambling throughout the night, causing gamblers to lose sleep.
Psychological factors also affect the sleep of gamblers. Mood disorders, anxiety disorders, and substance-related disorders are among the most common comorbid conditions of pathological gambling.16
Interestingly, insomnia is an important feature of these disorders,76,77
and the presence of these comorbid disorders may contribute to problems with sleep in gamblers. Shame, guilt, depression, helplessness, and anger are all commonly experienced in pathological gamblers. These feelings become worse as the gambling disorder progresses. Even when criteria are not met for a formal psychiatric diagnosis, the negative or dysphoric affect and state of mind of the gambler can have a significant effect on sleep. The preoccupation with gambling, reliving past gambling experiences, planning next gambling sessions, and thinking about ways to get money to gamble2
can further contribute to the disturbed sleep and stress. Extreme amounts of stress are common in pathological gamblers,13
and evidence is mounting that suggests that this stress also adversely affects sleep.78
Several biological mechanisms may be useful in explaining the sleep problems of gamblers. Of particular interest is the recent work examining the role of clock genes in human biology and disease, particularly mental illness. Clock genes, which code for proteins that regulate the circadian rhythm and the leep/wake cycle, have been implicated not only in sleep disorders, but also in substance abuse disorders and other psychiatric illness, most notably depression and bipolar disorder.79–82
The expression of these clock genes is altered by the use of psychoactive drugs or during the process of psychiatric disease and sleep disorders.79–82
Interestingly, a bi-directional association has been found whereby not only do drugs of abuse have an effect on the expression of these clock genes, but the differential expression of these clock genes in turn influences the consequences of using psychoactive drugs.80,81
Given the substantial role for clock genes in substance abuse, mental illness, and sleep disorders, they may serve a similar function in gambling disorders.
Conversely, problematic sleep may have a significant effect on gambling outcomes. Recent studies have demonstrated that sleep disturbances impair self-control and decision-making,83,84
increase impulsivity, attenuate responses to losses and increase expectations of gains,85
and degrade cognition in executive functioning tasks,86,87
which may suggest that problematic sleep could increase the risk for development of more severe gambling. Substance abusers, who often acquire sleep problems, are known to use drugs to self-medicate and cope with these issues.51,88–90
Similarly, pathological gamblers may gamble as an escape from their sleep problems, as well as anxiety and depression, and this use of gambling as a coping mechanism is even listed in the DSM-IV as one of the 10 diagnostic criteria for the disorder. Along with the recent findings on impulsivity and impaired decision making, this suggests that a bi-directional association may be present, whereby poor sleep promotes detrimental gambling behavior, and disordered gambling in turn adversely affects sleep. Such a positive feedback loop would promote the progression of gambling disorders. Future studies may choose to examine the causal nature of this relationship and investigate which of the two more frequently predicts the other.
The clinical implications of disturbed sleep in gamblers are plentiful. Sleep problems currently receive no mention in the DSM-IV description of pathological gambling,2
and evidence-based treatments for gambling do not include the management of sleep disturbances.91,92
In light of this, treatment providers may be unaware that this population is at risk for poor sleep. Problematic sleep is associated with increased risk of motor vehicle accidents, significantly decreased work productivity, increased risk of suicide, excessive use of health care, and decreased quality of life.24–26,31–33
These associations may intensify the impact inflicted from gambling disorders. In addition, benefits have been shown for the treatment of problematic sleep in other psychiatric conditions, including substance abuse.54,77,93–99
Bootzin and Stevens77
even suggest that the treatment of insomnia associated with substance use withdrawal may be an effective strategy in aiding in the prevention of relapse.
The sample size of this study was the chief limitation. A larger sample size would have allowed greater control for potential confounders, such as comorbid psychiatric disorders. However, because the frequency of psychiatric and substance related disorders is high for disordered gamblers (57.5% for substance use disorders, 37.9% for mood disorders, and 37.4% for anxiety disorders),5,16
examining sleep in disordered gamblers without these comorbidities may be clinically inapplicable. Due to this study’s sample size, it was statistically challenging to explore the specific relationship between sleep disturbances and preferred gambling behavior because several independent gambling factors may play a role in the development of sleep disturbances (e.g., duration, frequency, and amount spent gambling). A larger dataset would allow a multiple logistic regression analysis to account for several independent variables, such as hours played, number of days played, and dollars gambled. Lastly, the nature of questionnaires is that they typically create some recall bias.72
Future studies may attempt to use more objective sleep measures such as polysomniography.
Despite these limitations, this study was able to take a reliable cross-sectional glance at the landscape of sleep disturbances within a severity distribution of gamblers. This was the first study to find an association between problematic sleep and gambling severity using valid and reliable sleep measures in non-treatment seeking gamblers. Hopefully, these findings will not only increase awareness of this relationship, but also provide a foundation on which others can investigate the benefits of screening and adjunct treatment for sleep disorders in the gambling population.