Brain Networks, Neurotransmitters and Psychedelics: Towards a Neurochemistry of Self-Awareness

PURPOSE OF REVIEW

Self-awareness can be defined as the capacity of becoming the object of one's own awareness and, increasingly, it has been the target of scientific inquiry. Self-awareness has important clinical implications, and a better understanding of the neurochemical basis of self-awareness may help clarifying causes and developing interventions for different psychopathological conditions. The current article explores the relationship between neurochemistry and self-awareness, with special attention to the effects of psychedelics.

RECENT FINDINGS

The functioning of self-related networks, such as the default-mode network and the salience network, and how these are influenced by different neurotransmitters is discussed. The impact of psychedelics on self-awareness is reviewed in relation to specific processes, such as interoception, body ownership, agency, metacognition, emotional regulation and autobiographical memory, within a framework based on predictive coding. Improved outcomes in emotional regulation and autobiographical memory have been observed in association with the use of psychedelics, suggesting higher-order self-awareness changes, which can be modulated by relaxation of priors and improved coping mechanisms linked to cognitive flexibility. Alterations in bodily self-awareness are less consistent, being potentially impacted by doses employed, differences in acute/long-term effects and the presence of clinical conditions. Future studies investigating the effects of different molecules in rebalancing connectivity between resting-state networks may lead to novel therapeutic approaches and the refinement of existing treatments.

Validation of the Psychological Insight Scale: A new scale to assess psychological insight following a psychedelic experience

INTRODUCTION

As their name suggests, 'psychedelic' (mind-revealing) compounds are thought to catalyse processes of psychological insight; however, few satisfactory scales exist to sample this. This study sought to develop a new scale to measure psychological insight after a psychedelic experience: the Psychological Insight Scale (PIS).

METHODS

The PIS is a six- to seven-item questionnaire that enquires about psychological insight after a psychedelic experience (PIS-6) and accompanied behavioural changes (PIS item 7). In total, 886 participants took part in a study in which the PIS and other questionnaires were completed in a prospective fashion in relation to a planned psychedelic experience. For validation purposes, data from 279 participants were analysed from a non-specific 'global psychedelic survey' study.

RESULTS

Principal components analysis of PIS scores revealed a principal component explaining 73.57% of the variance, which displayed high internal consistency at multiple timepoints throughout the study (average Cronbach's α = 0.94). Criterion validity was confirmed using the global psychedelic survey study, and convergent validity was confirmed via the Therapeutic-Realizations Scale. Furthermore, PIS scores significantly mediated the relationship between emotional breakthrough and long-term well-being.

CONCLUSION

The PIS is complementary to current subjective measures used in psychedelic studies, most of which are completed in relation to the acute experience. Insight - as measured by the PIS - was found to be a key mediator of long-term psychological outcomes following a psychedelic experience. Future research may investigate how insight varies throughout a psychedelic process, its underlying neurobiology and how it impacts behaviour and mental health.

Twenty percent better with 20 micrograms? A qualitative study of psychedelic microdosing self-rapports and discussions on YouTube

BACKGROUND

Psychedelic microdosing is the trending practice of using tiny repeated doses of psychedelic substances to facilitate a range of supposed benefits. With only a few published studies to date, the subject is still under-researched, and more knowledge is warranted. Social media and internet discussion forums have played a vital role in the growing visibility of the microdosing phenomenon, and the present study utilized YouTube contents to improve comprehension of the microdosing practice as well as the social interactions and discussions around microdosing.

METHODS

Microdosing self-disclosure in YouTube videos and their following comments were qualitatively analyzed by inductive thematic analysis. Various software was utilized to enable gathering and sorting relevant data.

RESULTS

Microdosing of psychedelic substances, primarily LSD and psilocybin, was used for therapeutic and enhancement purposes, and predominantly beneficial effects were reported. Many different applications and outcomes were discussed, and therapeutic effects for depression appeared especially noteworthy. Intentions for use were recognized as an influencing factor for the progression and outcomes of microdosing. The function of social interactions was mainly to discuss views on the microdosing phenomenon, strategies for optimal results, minimize risks, and share emotional support.

CONCLUSIONS

Potentially, microdosing could provide some of the same benefits (for certain conditions) as full-dose interventions with less risk of adverse reactions related to the sometimes intense experiences of higher doses. Microdosing may well also mean additional benefits, as well as risks, through the repeated exposure over extended periods.

Recovery from Bispectral Index-guided Anaesthesia in a Large Randomized Controlled Trial of Patients at High Risk of Awareness

Electroencephalographic monitors of anaesthetic depth are reported to assist anaesthetists in reducing recovery times. We explored the effect of bispectral index (BIS) monitoring on recovery times in a double-blind, randomized controlled trial of 2,463 patients at high risk of awareness. Patients were randomized to BIS-guided anaesthesia or routine care. In the BIS group, anaesthesia was adjusted to maintain a BIS value of 40–60 from the commencement of laryngoscopy to the start of wound closure, and 55–70 during wound closure. In the routine care group, anaesthesia was adjusted according to traditional clinical signs. In multivariate models, BIS monitoring, female gender, lower American Society of Anesthesiologists’ physical status and shorter duration of anaesthesia predicted faster time to eye-opening after anaesthesia, and faster time to post-anaesthesia care unit discharge. BIS monitoring did not affect times to tracheal extubation among patients admitted to the intensive care unit. We conclude that BIS monitoring has statistically significant, but clinically modest, effects on recovery times in high risk surgical patients.

Bispectral Index during Modified Rapid Sequence Induction Using Thiopentone or Propofol and Rocuronium

This randomized controlled trial compared Bispectral Index (BIS) values in 40 patients after a modified rapid sequence induction using thiopentone 4 mg/kg or propofol 2 mg/kg with rocuronium 0.6 mg/kg as muscle relaxant. Endotracheal intubation was performed at 60 seconds from induction of anaesthesia and BIS values were recorded for three minutes after induction. At the 120, 150 and 180 second measurements there was a significantly greater proportion of subjects with BIS values ≤ 60 (“anaesthetized”) in the propofol group compared with the thiopentone group (P values <0.02, <0.01 and <0.01 respectively).

All intubations were completed within two minutes. No explicit recall of intubation was detected clinically with either induction agent. The BIS scores we have measured suggest that thiopentone 4 mg/kg is more likely to be associated with lighter planes of anaesthesia and consequent risk of awareness than propofol 2 mg/kg, if intubation is delayed or prolonged.

Pre-sleep treatment with galantamine stimulates lucid dreaming: A double-blind, placebo-controlled, crossover study

Lucid dreaming is a remarkable state of consciousness in which one is aware of the fact that one is dreaming while continuing to dream. Based on the strong relationship between physiological activation during rapid eye-movement sleep and lucid dreaming, our pilot research investigated whether enhancing cortical activation via acetylcholinesterease inhibition (AChEI) would increase the frequency of lucid dreams and found AChEI to be a promising method for lucid dream induction. In the current study we sought to quantify the size and reliability of the effect of AChEI on lucid dreaming, dream recall and dream content as well as to test the effectiveness of an integrated lucid dream induction protocol which combined cholinergic stimulation with other methods for lucid dream induction. Participants (N = 121) with high dream recall and an interest in lucid dreaming were randomly assigned counterbalanced orders of 3 doses of galantamine (0, 4 and 8 mg). On 3 consecutive nights, they awoke approximately 4.5 hours after lights out, recalled a dream, ingested the capsules and stayed out of bed for at least 30 minutes. Participants then returned to bed and practiced the Mnemonic Induction of Lucid Dreams technique while returning to sleep. The percentage of participants who reported a lucid dream was significantly increased for both 4 mg (27%, odds ratio = 2.29) and 8 mg doses (42%, odds ratio = 4.46) compared to the active placebo procedure (14%). Galantamine also significantly increased dream recall, sensory vividness and complexity (p<0.05). Dream recall, cognitive clarity, control, positive emotion, vividness and self-reflection were increased during lucid compared to non-lucid dreams (p<0.0001). These results show that galantamine increases the frequency of lucid dreams in a dose-related manner. Furthermore, the integrated method of taking galantamine in the last third of the night with at least 30 minutes of sleep interruption and with an appropriately focused mental set is one of the most effective methods for inducing lucid dreams available today.

The effects of alcohol on heartbeat perception: Implications for anxiety

INTRODUCTION

It is well established that some individuals self-medicate their anxiety with alcohol. Though much evidence exists that alcohol consumption can be negatively reinforcing, there remains uncertainty regarding what mediates the relationship between alcohol and anxiety. An unexplored possibility is that, for some, alcohol impairs interoceptive sensitivity (the ability to accurately perceive one's physiological state), thereby decreasing state anxiety. Consistent with this, highly accurate heartbeat perception is a risk factor both for elevated trait anxiety and anxiety disorders. However, the direct impact of alcohol on cardioceptive accuracy has not to our knowledge been previously examined.

METHODS

Sixty-one social drinkers came to the lab in groups of 4-6 on two days spaced a week apart. Each participant was randomly assigned to receive alcoholic drinks targeting a BAC of 0.05% on one testing day and placebo drinks on the other, with the order counter-balanced. On both testing days, participants engaged in a Schandry heartbeat perception task on three occasions: at baseline, after an alcohol absorption period, and after physiological arousal was raised via exercise.

RESULTS

For men only, alcohol significantly impaired cardioceptive accuracy relative to a placebo at both low and high levels of arousal, with medium to large effect sizes.

CONCLUSIONS

Though preliminary, this finding is consistent with the proposed hypothesis linking alcohol consumption and anxiety, at least for men. Future studies should directly examine whether, among individuals with anxiety disorders, cardioceptive sensitivity mediates the relationship between alcohol consumption and state anxiety.

Anaesthesia for Bronchoscopy: Examination of a Standard Technique

An anaesthetic technique for bronchoscopy is described, based on increments of methohexitone given in strict relation to body weight and time, suxamethonium being used to produce relaxation. There was no awareness in the 75 patients studied, while the recovery was rapid and unrelated to the duration of bronchoscopy. The efficacy of small aliquots of lignocaine in reducing injection pain was the same whether given before, or mixed with, the initial methohexitone injection. Other sequelae relating to the anaesthetic technique were minimal.

Levodopa medication improves incidental sequence learning in Parkinson's disease

Empirical evidence suggests that levodopa medication used to treat the motor symptoms of Parkinson's disease (PD) may either improve, impair or not affect specific cognitive processes. This evidence led to the 'dopamine overdose' hypothesis that levodopa medication impairs performance on cognitive tasks if they recruit fronto-striatal circuits which are not yet dopamine-depleted in early PD and as a result the medication leads to an excess of dopamine. This hypothesis has been supported for various learning tasks including conditional associative learning, reversal learning, classification learning and intentional deterministic sequence learning, on all of which PD patients demonstrated significantly worse performance when tested on relative to off dopamine medication. Incidental sequence learning is impaired in PD, but how such learning is affected by dopaminergic therapy remains undetermined. The aim of the current study was to investigate the effect of dopaminergic medication on incidental sequence learning in PD. We used a probabilistic serial reaction time task (SRTT), a sequence learning paradigm considered to make the sequence less apparent and more likely to be learned incidentally rather than intentionally. We compared learning by the same group of PD patients (n=15) on two separate occasions following oral administration of levodopa medication (on state) and after overnight withdrawal of medication (off state). Our results demonstrate for the first time that levodopa medication enhances incidental learning of a probabilistic sequence on the serial reaction time task in PD. However, neither group significantly differed from performance of a control group without a neurological disease, which indicates the importance of within group comparisons for identifying deficits. Levodopa medication enhanced incidental learning by patients with PD on a probabilistic sequence learning paradigm even though the patients were not aware of the existence of the sequence or their acquired knowledge. The results suggest a role in acquiring incidental motor sequence learning for dorsal striatal areas strongly affected by dopamine depletion in early PD.

Arousal withiv epinephrine depends on the depth of anesthesia

PURPOSE

To investigate whether the depth of anesthesia affects the change in the bispectral index (BIS) caused by iv epinephrine during propofol anesthesia.

METHODS

Forty women undergoing elective lower abdominal surgery received a propofol target controlled infusion (TCI) to maintain a modified Observer's Assessment of Alertness/Sedation (OAA/S) score of 2 (sedation period). Subsequently anesthesia was induced with propofol TCI 5 mug.mL(-1) and rocuronium 0.9 mg.kg(-1), and propofol continued so as to maintain general anesthesia at a BIS of 50 (general anesthesia period). Intravenous epinephrine at a dose of 10 mug.5 mL(-1) in normal saline (epinephrine group, n = 20) or normal saline 5 mL (control group, n = 20) was administered during both periods. The BIS, mean arterial pressure (MAP) and heart rate (HR) were measured immediately before, and one, two, three, four, six, eight, and ten minutes after injection. The modified OAA/S scale was evaluated during the sedation period.

RESULTS

There was no significant change in the modified OAA/S scale, BIS, or hemodynamic variables compared to preinjection values during either sedation or general anesthesia in the control group. Intravenous epinephrine increased the BIS and modified OAA/S scale during sedation, but there was no increase in BIS during general anesthesia. Increases in HR and MAP were observed during both periods after iv epinephrine.

CONCLUSION

Intravenous epinephrine 10 mug resulted in an arousal effect and an increase in BIS during sedation, but did not change the BIS during general anesthesia. These results suggest that the arousal effect of iv epinephrine during propofol anesthesia depends on anesthetic depth.

[Is it possible to measure the depth of anesthesia using electroencephalogram?]

Although anesthetic monitoring has rapidly developed over the past few years, accidental awareness during general anesthesia still remains a significant clinical problem. It occurs in one out of thousand surgical patients. In addition to conventional clinical signs, the adequacy of anesthesia can be assessed for instance by monitoring the changes occurring in the electroencephalogram (EEG). The EEG effects of different anesthetics are, however, highly varied, and attempts to develop an unequivocal neurophysiological measure or quantity for human consciousness or unconsciousness have so far been unsuccessful.

Postdischarge events occurring after pediatric sedation for dentistry

PURPOSE

To investigate postdischarge events occurring in children during the 24 hours following sedation for dentistry.

METHODS

A convenience sample of 50 children undergoing sedation with combinations of midazolam, hydroxyzine, and meperidine were included. Parents received a standardized timesheet to record child's behavior, alertness, activity level, motor imbalance, emesis, and soft tissue trauma every two hours from discharge until bedtime. A questionnaire asked about transportation, supervision, and return to normal activity. Families were telephoned after 24 hours to collect the information.

RESULTS

Sixty-six percent of children slept in the car; of these, 30 percent were supervised by only the driver, and 12 percent were difficult to awaken. Agitation was observed in 22 percent, restlessness in 10 percent, withdrawn behavior in 16 percent, and soft tissue trauma in 18 percent. Motor imbalance was significantly associated with midazolam (P=.002), as was restlessness (P=.004). Eighty-two percent slept between discharge and bedtime, with 16 percent sleeping for greater than four hours. Return to normal activity was greater than four hours in 36 percent, and was inversely correlated with age (P=.02).

CONCLUSIONS

Postdischarge sleepiness, drug-specific motor imbalance, sleep during transit, and recovery times greater than four hours were common and warrant vigilant adult supervision.

Naturalistic conversation improves daytime motorway driving performance under a benzodiazepine: a randomised, crossover, double-blind, placebo-controlled study

The adverse effects of benzodiazepines on driving are widely recognised. The aims of this study were both to determine the impact of naturalistic conversation on the driving ability of drivers under a benzodiazepine, and to measure the accuracy of drivers' assessments of the joint effects of the benzodiazepine and conversation. Sixteen healthy male participants (29.69 ± 3.30 years) underwent a randomised, crossover, double-blind, placebo-controlled study with the benzodiazepine lorazepam (2mg). They drove 200 km (125 miles) on a motorway in the morning. We measured two driving ability-related variables (i.e., lane-keeping performance), and collected a set of self-assessed variables (i.e., self-assessment of driving performance) during two 10-min sequences of interest (no conversation vs. conversation). An analysis of variance revealed an interaction whereby lane-keeping performance under lorazepam was worse in the no-conversation condition than in the conversation condition. No such difference was detected under placebo. Pearson's correlation coefficients revealed that self-assessments were (i) not at all predictive of lane-keeping when performed before the drive, but (ii) moderately predictive of lane-keeping performance when performed during or after the drive. We conclude that conversation with a passenger may contribute to safer lane-keeping when driving under a benzodiazepine. Moreover, a degree of awareness may be attained after some experience of driving under the influence of this type of medication.

Pharmacological modulation of the state of awareness in patients with disorders of consciousness: an overview

The neurobiological approach to consciousness moves from the assumption that all phenomenal experiences are based on neuronal activity in the brain. Consciousness has two main components: wakefulness and awareness. While it may be relatively easy to determine the neuronal correlates of wakefulness, it is not the same for awareness, of which the neural correlates are poorly understood. Knowledge of the circuitry and the neurochemistry of the sleep/wake condition is necessary but not sufficient to understand the circuitry and neurochemistry of consciousness. Disorders of consciousness (DOCs) include coma, vegetative state and minimally conscious state. The study of DOCs and of the electrophysiological changes underlying general anaesthesia-induced loss of consciousness may help in understanding the neuronal correlates of consciousness. In turn, the understanding of the neural bases of consciousness may help in designing interventions aimed at restoring consciousness in DOC patients. Sporadic cases of recovery from a DOC have been reported after the administration of various pharmacological agents (baclofen, zolpidem, amantadine etc.). This review provides an overview of such drugs, which are from various and diverging classes but can be grouped into two main categories: CNS stimulants and CNS depressants. The available data seem to suggest an awakening effect obtained with CNS depressants rather than stimulants, the latter being more effective at improving functional cognitive and behavioral recovery in patients who have spontaneously regained an appreciable level of consciousness. There is a need for more rigorous systematic trials and further investigation of the above treatments, with particular attention paid to their mechanisms of action and the neurotransmitters involved.

The effects of energy drink in combination with alcohol on performance and subjective awareness

RATIONALE

This study investigated the coadministration of an energy drink with alcohol to study the effects on subjective intoxication and objective performance.

OBJECTIVES

This study aims to evaluate the objective and subjective effects of alcohol versus placebo at two alcohol doses, alone and in combination with an energy drink, in a balanced order, placebo-controlled, double-blind design.

METHODS

Two groups of ten healthy volunteers, mean (SD) age of 24 (6.5), participated in the study. One group consumed energy drink containing 80 mg of caffeine and the other consumed a placebo drink, with both receiving two alcohol doses (0.046 and 0.087% breathalyser alcohol concentration). Tests included breath alcohol assessment, objective measures of performance (reaction time, word memory and Stroop task) and subjective visual analogue mood scales.

RESULTS

Participants showed significantly impaired reaction time and memory after alcohol compared to the no alcohol condition and had poorer memory after the higher alcohol dose. Stroop performance was improved with the energy drink plus alcohol combination compared to the placebo drink plus alcohol combination. Participants felt significant subjective dose-related impairment after alcohol compared to no alcohol. Neither breath alcohol concentration nor the subjective measures showed a significant difference between the energy drink and the placebo energy drink when combined with alcohol.

CONCLUSIONS

Subjective effects reflected awareness of alcohol intoxication and sensitivity to increasing alcohol dose. There were no overall significant group differences for subjective measures between energy drink and placebo groups in the presence of alcohol and no evidence that the energy drink masked the subjective effects of alcohol at either dose.

Oxytocin increases recognition of masked emotional faces

The neuropeptide oxytocin has been shown to improve many aspects of social cognitive functioning, including facial emotion recognition, and to promote social approach behaviour. In the present study, we investigated the modulatory effects of oxytocin on the recognition of briefly presented facial expressions. In order to diversify the degree of visual awareness for the facial stimuli, presentation duration was systematically varied. Fifty-six participants were administered intranasal oxytocin or a placebo in a double-blind, randomized, between-subjects design. Participants viewed angry and happy target faces or neutral distractors for 18, 35, or 53 ms subsequently masked by neutral faces. Participants had to indicate the presence or absence of the briefly presented target face. Discrimination indices (d') showed that oxytocin generally enhanced detection accuracy of emotional stimuli. This effect was more pronounced for the recognition of happy faces. We provide evidence that a single dose of intranasally administered oxytocin enhances detection of briefly presented emotional stimuli. The possible role of stimulus valence and recognition difficulty is discussed.

Dexamphetamine effects on separate constructs in the rubber hand illusion test

RATIONALE

Corporeal awareness is an integral component of self-consciousness and is distorted in several neurological and psychiatric disorders. Research regarding the neural underpinnings of corporeal awareness has made much progress recently using the rubber hand illusion (RHI) procedure. However, more studies are needed to investigate the possibility of several dissociable constructs related to the RHI specifically, and corporeal awareness generally.

OBJECTIVES

Considering dopamine's involvement in many perceptual-motor learning processes, as well as its apparent relationship with disorders such as schizophrenia that are linked to body ownership disturbances, we gave 0.45 mg/kg dexamphetamine (a dopamine transporter reverser) to 20 healthy participants to examine the effects of increased dopamine transmission on the RHI.

METHODS

The effect of dexamphetamine on separate quantitative constructs underlying RHI were examined including embodiment of rubber hand, loss of ownership of real hand, perception of movement, affect, deafference, and proprioceptive drift. The experiment was a double-blind, placebo-controlled, cross-over design.

RESULTS

Dexamphetamine increased participants' ratings of embodiment (particularly "ownership") of the rubber hand and was associated with the experience of loss of ownership of the person's real hand. There were significant increases from asynchronous to synchronous stroking for the measures of movement and proprioceptive drift after placebo but not dexamphetamine. There were no changes in the measures of other constructs.

CONCLUSIONS

These results show a novel pharmacological manipulation of separate constructs of the RHI. This finding may aid in our understanding of disorders that have overlapping disturbances in both dopamine activity and body representations, particularly schizophrenia.

The Richmond Agitation-Sedation Scale: translation and reliability testing in a Swedish intensive care unit

BACKGROUND

Awareness about adequate sedation in mechanically ventilated patients has increased in recent years. The use of a sedation scale to continually evaluate the patient's response to sedation may promote earlier extubation and may subsequently have a positive effect on the length of stay in the intensive care unit (ICU). The Richmond Agitation-Sedation Scale (RASS) provides 10 well-defined levels divided into two different segments, including criteria for levels of sedation and agitation. Previous studies of the RASS have shown it to have strong reliability and validity. The aim of this study was to translate the RASS into Swedish and to test the inter-rater reliability of the scale in a Swedish ICU.

METHODS

A translation of the RASS from English into Swedish was carried out, including back-translation, critical review and pilot testing. The inter-rater reliability testing was conducted in a general ICU at a university hospital in the south of Sweden, including 15 patients mechanically ventilated and sedated. Forty in-pair assessments using the Swedish version of the RASS were performed and the inter-rater reliability was tested using weighted kappa statistics (linear weighting).

RESULT

The translation of the RASS was successful and the Swedish version was found to be satisfactory and applicable in the ICU. When tested for inter-rater reliability, the weighed kappa value was 0.86.

CONCLUSION

This study indicates that the Swedish version of the RASS is applicable with good inter-rater reliability, suggesting that the RASS can be useful for sedation assessment of patients mechanically ventilated in Swedish general ICUs.

Effect of epidural dexmedetomidine on intraoperative awareness and post-operative pain after one-lung ventilation

BACKGROUND

During combined general and regional anaesthesia, it is difficult to use autonomic signs to assess whether wakefulness is suppressed adequately. We compared the effects of a dexmedetomidine-bupivacaine mixture with plain bupivacaine for thoracic epidural anaesthesia on intraoperative awareness and analgesic benefits, when combined with superficial isoflurane anaesthesia (<0.05 maximum alveolar concentration) in patients undergoing thoracic surgery with one-lung ventilation (OLV).

METHODS

Fifty adult male patients were randomly assigned to receive either epidural dexmedetomidine 1 microg/kg with bupivacaine 0.5% (group D) or bupivacaine 0.5% alone (group B) after induction of general anaesthesia. Gasometric, haemodynamic and bispectral index values were recorded. Post-operative verbal rating score for pain and observer's assessment of alertness/sedation scale were determined by a blinded observer.

RESULTS

Dexmedetomidine reduced the use of supplementary fentanyl during surgery. Patients in group B consumed more analgesics and had higher pain scores after operation than patients of group D. The level of sedation was similar between the two groups in the ICU. Two patients (8%) in group B reported possible intraoperative awareness. There was a limited decrease in PaO2 at OLV in group D compared with group B (P<0.05).

CONCLUSION

In thoracic surgery with OLV, the use of epidural dexmedetomidine decreases the anaesthetic requirements significantly, prevents awareness during anaesthesia and improves intraoperative oxygenation and post-operative analgesia.

Out for a smoke: the impact of cigarette craving on zoning out during reading

Cigarette craving has powerful effects on cognitive functioning, which may promote smoking behavior and relapse. One area of cognition that has had little impact on craving research is human consciousness. Developments in consciousness research using a mindless-reading paradigm permit examination of the effects of craving on both the occurrence and the awareness of mental lapses. Forty-four smokers, who were either nicotine deprived (crave condition) or nondeprived (low-crave condition), performed a mindless-reading task. This task assesses both self-caught and probe-caught mind-wandering episodes to distinguish between lapses that are within and outside of awareness. Compared with the low cravers, those in the cigarette-crave condition were significantly more likely to acknowledge that their mind was wandering when they were probed. When we adjusted for this more-than-threefold increase in zoning out, craving also lowered the probability of catching oneself. Results suggest that craving simultaneously increases mental lapses while reducing the metacognitive capacity to notice them.