External validity of the reduced Morningness-Eveningness Questionnaire for Children and Adolescents: an actigraphic study.

The aim of this study was to examine the external validity of the reduced Morningness-Eveningness Questionnaires for Children and Adolescents, using circadian motor activity, assessed through actigraphy, as an external criterion. Overall, 458 participants (269 females), with a mean (standard deviation) age of 15.75 (1.16) years, took part in this study. Each adolescent was requested to wear the actigraph Micro Motionlogger Watch actigraph (Ambulatory Monitoring, Inc., Ardlsey, NY, USA) around the non-dominant wrist for 1 week. At the end of the actigraphic recording, participants completed the reduced Morningness-Eveningness Questionnaires for Children and Adolescents. We extracted the motor activity counts, minute-by-minute over the 24 h, to depict the 24-h motor activity pattern, and we adopted the statistical framework of functional linear modelling to examine its changes according to chronotype. According to the reduced Morningness-Eveningness Questionnaires for Children and Adolescents cut-off scores, 13.97% of participants (n = 64) belonged to the evening-types category, 9.39% (n = 43) to morning-types, while the remaining (76.64%, n = 351) to the intermediate-types category. Evening types moved significantly more than the intermediate and morning types from around 10:00 p.m. to 2:00 a.m., while the opposite pattern of results was observed around 4:00 a.m. The results highlighted a significant difference in the 24-h motor activity pattern between chronotypes, in line with the expectations based on their well-known behaviour. Therefore, this study shows that the external validity of the reduced Morningness-Eveningness Questionnaire for Children and Adolescents, established by considering motor activity (recorded through actigraphy) as an external criterion, is satisfactory.

Sleep during COVID-19-related school lockdown, a longitudinal study among high school students.

There has been great concern about the impact of coronavirus disease 2019 (COVID-19)-related school lockdown on adolescent health. The aim of the present study was to compare sleep patterns before and during COVID-19-related school lockdown, in a large sample of high school students. The present study is based a prospective, longitudinal survey on adolescent sleep health. Phase 1 was conducted in 2019, whereas phase 2 was conducted in 2020 (response rate 60.2%), during the last 10 days of a 60-day long school lockdown. Main outcomes comprised sleep parameters from the Munich ChronoType Questionnaire (MCTQ). A total of 2,022 students provided valid responses to MCTQ in both survey phases. Results showed later sleep timing on schooldays in 2020 compared to 2019 (36 min later bedtimes, Cohen's d = 0.56; 1:35 hr later rise times, Cohen's d = 1.44). Time spent in bed on schooldays increased from 8:20 to 9:19 hr (Cohen's d = 0.78), and sleep duration increased by 45 min (Cohen's d = 0.49). The proportion of adolescents obtaining the recommended ≥8 hr of sleep on schooldays increased from 13.4% (2019) to 37.5% during the lockdown. Social jetlag was reduced from 2:37 hr (2019) to 1:53 hr (2020, Cohen's d = 0.59). Results points to a potential advantageous effect of school lockdown in terms of increased school day sleep duration and reduced social jetlag. As sleep is important for mental and somatic health, it is conceivable that increased sleep duration offered some protection against harmful aspects of the COVID-19 pandemic and associated social restrictions. Future studies should address possible associations between sleep changes and health during COVID-19-related school lockdown.

Synchrony effect on joint attention.

Research on joint attention has demonstrated that individuals are sensitive to a coactor's attentional relation to jointly attended stimuli. Within a chronobiological approach, a study was conducted to assess whether the presence of joint attention, as measured by the joint Navon effect, was influenced by the synchrony effect. Pairs of participants sitting next to each other were required to respond to the identity letters in a go/no-go Navon task. The joint Navon task was performed by morning, intermediate and evening types (81 pairs) at different times of day (09:00-10:00; 13:00-14:00; 17:00-18:00). The joint Navon effect on task performance was highlighted at the optimal time of day (in the morning for morning types, in the early afternoon for intermediate types and in the evening for evening types), but it disappeared or decreased at the non-optimal time of day, with the exception of evening types. The results demonstrated that joint attention was affected by the synchrony effect.

Circadian typology and the Alternative Five-Factor Model of personality.

Two studies were carried out to explore the relationship between circadian typology and the Alternative Five-Factor Model of personality. In the first study, 379 participants (232 females) were administered the reduced version of the Morningness-Eveningness Questionnaire and the Zuckerman-Kuhlman Personality Questionnaire. Evening types reported higher impulsive sensation-seeking scores than morning and intermediate types, whereas morning types scored higher than evening types on activity factor. In the second study, the association between morningness and activity personality factor was verified through the objective-actigraphic monitoring of the rest-activity cycle. Actigraphy allowed us to operationalise both circadian typology, through the computing of midpoint of sleep (early values, expressed in hours and minutes, correspond to an advanced phase of the sleep/wake cycle), and activity factor by the means of motor activity recording. Fifty-one individuals (30 females) wore an actigraph on the nondominant wrist continuously for 1 week. A negative correlation was observed between midpoint of sleep and mean diurnal motor activity, demonstrating that an early phase of the sleep/wake cycle (i.e. morningness preference) was related to higher diurnal motor activity. Assessed both subjectively and objectively, the results of both studies highlight a significant relationship between morningness and activity personality factor.

The Japanese version of the reduced morningness-eveningness questionnaire.

Circadian typology, or "morningness" and "eveningness," is generally assessed using the Morningness-Eveningness Questionnaire (MEQ), a 19-item scale that could be burdensome in large-scale surveys. To overcome this, a 5-item version known as the reduced morningness-eveningness questionnaire (rMEQ), which is sensitive to the assessment of circadian typology, was developed; however, a validated Japanese version of the rMEQ is yet to be established. This study aimed to develop and validate the Japanese version of the rMEQ. Five essential items for the rMEQ were selected from existing Japanese MEQ data (N = 2,213), and the rMEQ was compiled. We conducted a confirmatory factor analysis for the psychometric properties of the rMEQ and confirmed its robust one-factor structure for evaluating morningness-eveningness (GFI = 0.984, AGFI = 0.951, CFI = 0.935, and RMSEA = 0.091). Reliability was evaluated via internal consistency of rMEQ items using Cronbach's α and McDonald's ω, and the values were 0.618 and 0.654, respectively. The rMEQ scores strongly correlated with MEQ (ρ = 0.883, p < 0.001), and classification agreement (Morning, Neither, and Evening types) between rMEQ and MEQ was 77.6% (Cramer's V = 0.643, Weighted Cohen's κ = 0.72), confirming the validity. The Japanese rMEQ may be a valuable tool for the efficient assessment of circadian typologies.

Physical activity and morningness: A helpful combination in improving the sleep quality of active Italian university students.

University students are commonly described as having worsened sleep quality, especially when inactive and Evening-type (E-type) subjects. This study aimed to examine the interactions between physical activity and chronotype on sleep quality among a sample of active Sports Science university students. In November 2019, 433 participants (mean age: 19.7 ± 1.56 years; 70% males) completed the Pittsburgh Sleep Quality Index, the Godin-Shepard Leisure-Time Physical Activity Questionnaire (tertiles categorisation), and the Morningness-Eveningness Questionnaire. Females and E-type slept significantly worse than males and Neither-(N-types) and Morning-types (M-types), respectively. However, there were no significant differences in sleep quality based on physical activity levels. The three-way ANOVA revealed that sleep quality in N- and E-types appeared to be independent of physical activity, whereas M-types showed an improvement in sleep classification with increased physical activity. Moderation analysis indicated that physical activity significantly moderated the relationship between chronotypes and sleep quality. Specifically, M-types demonstrated a more pronounced improvement in sleep quality with increasing physical activity compared to the other chronotypes. In conclusion, M-type university students derived the greatest benefits from physical activity in improving sleep quality. Conversely, physical activity seemed to have a limited impact on sleep quality among active E-type university students.

Mindfulness, Subjective Cognitive Functioning, Sleep Timing and Time Expansion during COVID-19 Lockdown: A Longitudinal Study in Italy.

During the COVID-19 lockdown, a distortion of time passage has been widely reported in association with a change in daily rhythm. However, several variables related to these changes have not been considered. The purpose of the present study was to assess the changes in dispositional mindfulness, time experience, sleep timing and subjective memory functioning. A longitudinal study was conducted on 39 Italian adults (53.85% males; 35.03 ± 14.02 years) assessing mindfulness, ad hoc questions of sleep habits during workdays and free days, chronotypes, subjective time experience, and memory functioning before (December 2019-March 2020) and during (April 2020-May 2020) the first Italian COVID-19 lockdown. Participants reported delayed sleep timing, a slowdown in the perception of the present time, a decrease of time pressure, and an increase in the feeling of time expansion/boredom. In addition to correlations between mindfulness, memory functioning, and subjective sleep duration during workdays, a mediation model showed that changes in the dispositional mindfulness determined a delay of bedtime during workdays through the mediation effect of increased feeling of time expansion/boredom. This finding highlighted the role of mindfulness in reducing the feeling of time expansion/boredom for regulating the sleep timing. The theoretical and practical implications of the findings are discussed.

The Relationship Between Circadian Typology and Dry Eye Symptoms in Chinese College Students.

Purpose: To explore the relationship between symptomatic dry eye and circadian typology in college students. Methods: This study included 269 students from 3 Chinese universities. All participants completed the ocular surface disease index (OSDI) questionnaire, the morningness-eveningness questionnaire (MEQ), and the Pittsburgh sleep quality index (PSQI) questionnaire. Participants were grouped into 3 types by the reduced MEQ (rMEQ) score:E-Type, N-Type, and M-Type. All these parameters were then analyzed for the effect on the severity of dry eye. Results: The occurrence rates of poor sleep quality (PSQI>5) and symptomatic dry eye (OSDI > 13) in the college students were 53.2% and 40.2%, respectively. The distribution of the circadian typology differed significantly among the college students with different dry eye severities (χ 2 = 59.44, P = 0. 000), and E-type was associated with the most severe dry eye symptoms. The OSDI and PSQI scores were both significantly different among college students with different chronotypes (F = 22.14, P = 0.000; F = 15.21, P = 0.000; respectively). For both scores, the E-type scored the highest, followed by N-type, and M-type was the lowest. The circadian typology was an independent factor for dry eye. The risk of E-Type was 6.99 times higher than that of M-Type (P = 0.000), and the risk of N-types was 3.23 times higher than that of M-Type (P = 0.000). Sleep quality was also an independent risk factor for dry eye (P = 0.000). Gender and awareness of dry eye were not risk factors for dry eye. Conclusion: The severity of dry eye symptoms and sleep quality were associated with different circadian typologies. The more the circadian preference tended to be E-type, the worse the sleep quality and the more serious dry eye symptoms would appear.

Morningness-Eveningness Preference, Time Perspective, and Passage of Time Judgments.

Recent studies have shown that making accurate passage of time judgments (POTJs) for long-time intervals is an important cognitive ability. Different temporal domains, such as circadian typology (biological time) and time perspective (psychological time), could have an effect on subjective POTJs, but few studies have investigated the reciprocal influences among these temporal domains. The present study is the first systematic attempt to fill this gap. A sample of 222 participants (53.20% females; 19-60 years) filled in the Zimbardo Time Perspective Inventory for the measurement of time perspective, the reduced version of the Morningness-Eveningness Questionnaire (rMEQ) for chronotypes, and an ad-hoc questionnaire assessing sleep habits during weekdays and the weekend (for social jetlag). The POTJ was measured using a modified version of a pictorial timeline presented at five different moments. Also, participants judged how different temporal expressions were related to the past, present, and future along a 7-point Likert scale. After confirming the association between eveningness and present-hedonism orientation and morningness and future-orientation, we found that evening-types produced higher scores for future expressions. The subjective POTJ expressed in minutes was predicted by Deviation from Balanced Time (DBTP), present-fatalism orientation, and social jetlag. Finally, the rMEQ score, past-positive orientation, and DBTP predicted the difference between subjective and objective POT. The results are discussed offering an explanation in terms of the interconnections between circadian typology, individual time perspective, and the sense of the POT, suggesting the multicomponent nature of the concept of time.

The relationship between circadian typology and lifetime experiences of hypomanic symptoms.

Circadian rhythms have been known to be associated with bipolar disorders. There are many cases in which hypomanic symptoms are not recognized as indicators of an illness. This study aimed to determine the correlation between the experience of lifetime hypomanic symptoms and circadian typology of university students. A total of 8,562 university students participated in the study. The participants completed the Composite Scale of Morningness (CSM) for circadian typology and Mood Disorder Questionnaire (MDQ). Chi-square test and analysis of variance were performed, and the post-hoc result was computed using the FDR adjusted p-values. Overall, the MDQ score was higher in the evening-type group. There was no significant difference between the intermediate-type group and morning-type group for male students. In the evening-type group, the positive response rate was significantly higher for 10 out of 13 items in the MDQ. The evening-type group was more likely to experience hypomanic symptoms. This study showed that circadian and seasonal characteristics related to circadian typology are associated with lifetime hypomanic symptoms. Hence, further investigation is needed to determine the eveningness trait, as it could be a trait marker of bipolar spectrum disorder.

Circadian typology and implications for adolescent sleep health. Results from a large, cross-sectional, school-based study.

STUDY OBJECTIVES: To investigate circadian typology in a large, representative sample of Norwegian adolescents, and its implications for sleep health. METHODS: The sample included 3920 1st year high school students aged 16-17 years. Respondents completed a web-based survey, including the short version of the Horne-Ostberg Morningness-Eveningness Questionnaire (rMEQ), the Munich Chronotype Questionnaire (MCTQ) and items on sleep-related behaviors (eg electronic media usage in bed, consumption of caffeinated beverages), sleep beliefs and daytime sleepiness. Data were analyzed using one-way ANOVAs and Chi-squared tests. RESULTS: In all, 7.8% were categorized as morning, 52.3% as intermediate and 39.9% as evening types, respectively. Evening types had later sleep timing, longer sleep latency, more social jetlag and shorter school day sleep duration than morning types, with intermediate types displaying a sleep pattern between these two extremes. None of the circadian types met the minimum recommended amount of sleep on school nights (ie 8+ hours), and only morning types had a mean sleep duration of 7+ hours (7:19 h, nearly 1 h more than evening types who slept 6:20 h, p < 0.001). Evening types reported more use of electronic media in bed, more consumption of caffeinated beverages and more daytime sleepiness than the other circadian types. They were also less satisfied with their school day sleep duration and perceived it more difficult to change their sleep pattern. CONCLUSIONS: Results from this study suggest that eveningness represents a sleep health challenge for older adolescents.

Biological Rhythm and Chronotype: New Perspectives in Health.

The circadian rhythm plays a fundamental role in regulating biological functions, including sleep-wake preference, body temperature, hormonal secretion, food intake, and cognitive and physical performance. Alterations in circadian rhythm can lead to chronic disease and impaired sleep. The circadian rhythmicity in human beings is represented by a complex phenotype. Indeed, over a 24-h period, a person's preferred time to be more active or to sleep can be expressed in the concept of morningness-eveningness. Three chronotypes are distinguished: Morning, Neither, and Evening-types. Interindividual differences in chronotypes need to be considered to reduce the negative effects of circadian disruptions on health. In the present review, we examine the bi-directional influences of the rest-activity circadian rhythm and sleep-wake cycle in chronic pathologies and disorders. We analyze the concept and the main characteristics of the three chronotypes.

Is Abdominal Fat Distribution Associated with Chronotype in Adults Independently of Lifestyle Factors?

Both abdominal obesity and its visceral component are independently associated with cardiometabolic diseases. Among the non-modifiable and modifiable determinants, lifestyle plays a central role, while chronotype is an emerging factor. Evening type (E-Type), more active and efficient in the last part of the day, has been associated with a health-impairing style, resulting in a higher risk of obesity and cardiometabolic diseases than morning type (M-Type). However, no study has examined the contribution of chronotype to abdominal fat distribution, even considering adherence to the Mediterranean diet (MD). We conducted a cross-sectional study on 416 adults (69.5% females, 50 ± 13 years). Waist circumference (WC), visceral fat (VAT) using ultrasonography, chronotype through the reduced Morningness-Eveningness Questionnaire (rMEQ), and adherence to MD were studied. Our results showed no differences in WC and VAT between chronotypes. However, adherence to MD resulted significantly lower in the E-Types compared to M-Types. WC decreased with increasing Mediterranean score and rMEQ score, and VAT decreased with increasing rMEQ score, indicating that E-Types have +2 cm of WC and +0.5 cm of VAT compared to M-Types. In conclusion, these results showed that chronotype is independently associated with abdominal obesity and visceral fat, underlining the potential implications of the individual circadian typology on abdominal obesity.

Heart Rate Variability in Sport Performance: Do Time of Day and Chronotype Play A Role?

A reliable non-invasive method to assess autonomic nervous system activity involves the evaluation of the time course of heart rate variability (HRV). HRV may vary in accordance with the degree and duration of training, and the circadian fluctuation of this variable is crucial for human health since the heart adapts to the needs of different activity levels during sleep phases or in the daytime. In the present review, time-of-day and chronotype effect on HRV in response to acute sessions of physical activity are discussed. Results are sparse and controversial; however, it seems that evening-type subjects have a higher perturbation of the autonomic nervous system (ANS), with slowed vagal reactivation and higher heart rate values in response to morning exercise than morning types. Conversely, both chronotype categories showed similar ANS activity during evening physical tasks, suggesting that this time of day seems to perturb the HRV circadian rhythm to a lesser extent. The control for chronotype and time-of-day effect represents a key strategy for individual training schedules, and, in perspective, for primary injury prevention.

Daily variation of visual sensitivity to luminance contrast: Effects of time of measurement and circadian typology.

This study analyzed the fluctuation of the achromatic visual contrast sensitivity (CS) of adult males (M = 23.42 ± 2.6 years) during a daily period. Twenty-eight volunteers were divided into three groups according to circadian typology (CT): moderate morning (MM; n = 8); intermediate (I; n = 10) and moderate evening (ME; n = 10). The Pittsburgh Sleep Quality Index was used to evaluate sleep quality, and the Horne and Ostberg Morningness-Eveningness Questionnaire was used to measure CT. To measure CS, we used Metropsis software version 11.0 with vertical sinusoidal grids of 0.2, 0.6, 1, 3.1, 6.1, 8.8, 13.2 and 15.6 cycles per degree of visual angle (cpd). The stimuli were presented on a cathode ray tube (CRT) color video monitor with a 19-inch flat screen, a 1024 × 786 pixel resolution, a 100 Hz refresh rate and a photopic luminance of 39.6 cd/m2. It was inferred that there is a tendency for visual contrast to vary according to daily rhythmicity and CT, mainly for the median spatial frequencies (1.0 cpd, χ2 = 9.93, p < 0.05 and 3.1 cpd, χ2 = 10.33, p < 0.05) and high spatial frequencies (13.2 cpd, χ2 = 11.54, p < 0.05) of ME participants. ME participants had minimal visual contrast sensitivity during the morning shift and a progressive increase from afternoon to night.

Differential effects of circadian typology on sleep-related symptoms, physical fatigue and psychological well-being in relation to resilience.

Various physiological and psychological functions are influenced by circadian typology (CT), which was reported to be related to resilience. However, few studies have assessed the effects of CT in relation to resilience. The aim of the present study was to assess the influence of CT on sleep-related symptoms, physical fatigue and psychological well-being in relation to resilience. The present study included a total of 1794 healthy hospital employees, and they completed the Morningness-Eveningness Questionnaire, Connor-Davidson Resilience Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Fatigue Severity Scale, Hospital Anxiety and Depression Scale and World Health Organization Quality of Life Scale Abbreviated Version. Subjects with evening type showed lower sleep quality, more daytime sleepiness and physical fatigue than neither types and morning types. Additionally, evening types were more depressed and anxious and reported a poorer quality of life. CT was found to be a significant predictor of sleep quality, but CT was minimally associated with physical fatigue and psychological well-being in the regression analysis. Instead, resilience was substantially related to all of the variables measured. In conclusion, CT independently predicts sleep quality, but the effects of CT on physical fatigue and psychological well-being are negligible compared to those of resilience.

Chronotype and response to training during the polar night: a pilot study.

BACKGROUND: An individual's chronotype influences his or her physiological rhythms. Some studies have looked at the effect of time of day on the responses to exercise, but studies on the effect of long-term training are lacking. OBJECTIVE: To report the effects of an 8-week training period during the polar night in non-athletes of different chronotypes living at 70°N. DESIGN: In all, 10 morning (M), 10 neither (N) and 10 evening (E) types were recruited, and their aerobic capacity (VO2max), strength, flexibility and balance before and after the training period were tested. RESULTS: 3 E-types, 5 N-types and 6 M-types completed the protocol. An increase in VO2max and strength was observed for the whole group. The best negative correlation (r=-0.5287) was found between the Morningness-Eveningness Questionnaire (MEQ) score and the increase in VO2max, and the best positive correlation (r=0.4395) was found between MEQ and the increase in strength. Changes in balance and flexibility did not show any clear trends. CONCLUSION: In an environment with no outdoor daylight, it seems that the response to 8 weeks of aerobic training is larger in the E- than in the M-types, although the M-types showed a larger improvement in strength.

Association between chronotype and nonrestorative sleep in a college population.

Nonrestorative sleep (NRS), characterized by a lack of refreshment upon awakening, has received little attention in the sleep literature even though it can occur and cause impairment apart from other sleep difficulties associated with insomnia. The Restorative Sleep Questionnaire (RSQ) is one of the first validated self-report instruments for investigating NRS severity, presenting new opportunities to explore what factors predict and perhaps contribute to unrefreshing sleep. The present study sought to determine whether inherent circadian preference for morning or evening activity, known as chronotype, predicted restorative sleep in 164 college undergraduates who completed daily RSQs over 2 weeks. The participants who endorsed greater orientation to evening activity on the morningness-eveningness questionnaire reported significantly less average restorative sleep across their full sampling period, and this association was maintained after accounting for demographic factors, number of sleep-relevant psychiatric and medical diagnoses, sleep diary parameters, self-reported status as an insomniac and ratings of sleep quality. When analyses were conducted separately for weekday and weekend RSQ scores, eveningness predicted NRS independently of extraneous variables only during the workweek, not during Saturday and Sunday. These findings have implications for the developing conceptualization of NRS, and continue the work of elucidating the interconnections between common sleep disturbances and the circadian system.

Morningness-eveningness and depressive symptoms: Test on the components level with CES-D in Polish students.

BACKGROUND: The study aimed to elucidate previously observed associations between morningness-eveningness and depressive symptomatology in university students. Relations between components of depressive symptomatology and morningness-eveningness were analysed. METHODS: Nine hundred and seventy-four university students completed Polish versions of the Centre for Epidemiological Studies - Depression scale (CES-D; Polish translation appended to this paper) and the Composite Scale of Morningness. Principal component analysis (PCA) was used to test the structure of depressive symptoms. Pearson and partial correlations (with age and sex controlled), along with regression analyses with morning affect (MA) and circadian preference as predictors, were used. RESULTS: PCA revealed three components of depressive symptoms: depressed/somatic affect, positive affect, interpersonal relations. Greater MA was related to less depressive symptoms in three components. Morning circadian preference was related to less depressive symptoms in depressed/somatic and positive affects and unrelated to interpersonal relations. Both morningness-eveningness components exhibited stronger links with depressed/somatic and positive affects than with interpersonal relations. Three CES-D components exhibited stronger links with MA than with circadian preference. In regression analyses only MA was statistically significant for positive affect and better interpersonal relations, whereas more depressed/somatic affect was predicted by lower MA and morning circadian preference (relationship reversed compared to correlations). LIMITATIONS: Self-report assessment. CONCLUSIONS: There are three groups of depressive symptoms in Polish university students. Associations of MA with depressed/somatic and positive affects are primarily responsible for the observed links between morningness-eveningness and depressive symptoms in university students. People with evening circadian preference whose MA is not lowered have less depressed/somatic affect.

Circadian rhythmicity in substance use disorder male patients with and without comorbid depression under ambulatory and therapeutic community treatment.

Although there have been described alterations of circadian rhythmicity both in patients with substance use disorder (SUD) and patients with major depressive disorder (MDD), the circadian characteristics of SUD patients with comorbid MDD (SUD-MDD) are unknown. Likewise, the possible influence of the different modalities of treatments (ambulatory or therapeutic community) upon the circadian rhythmicity of SUD patients has not been characterized. Therefore, this study analyzes the circadian rhythmic profiles of SUD and SUD-MDD patients under ambulatory and therapeutic community treatment. The sample was composed of 40 SUD and 40 SUD-MDD men, aged 22-55 yrs, under treatment and with abstinence for at least three months (including each group 20 ambulatory and 20 from therapeutic community). Patients completed a sociodemographic, clinical and sleep-wake schedules interview, the Composite Scale of Morningness, and wore on the wrist an ambulatory device known as iButton® Thermochron DS1921H, which registered their distal skin temperature every two minutes for 48 hours. All the groups showed a tendency to morningness without differences among them in concordance with their sleep-wake schedules. With regard to distal skin temperature circadian rhythm, SUD patients showed higher values than SUD-MDD in amplitude, relative amplitude, percentage rhythm, and first harmonic power, and lower minimum temperature in 10 consecutive hours (p < .043, in all cases). Therapeutic community group values were lower in minimum temperature and higher in amplitude, relative amplitude, and 12 harmonic accumulated power (p < .028, in all cases) as compared to ambulatory ones. Moreover, all groups showed higher Rayleigh vector and rhythm stability as compared to normative population (p < .043, in both cases). The circadian rhythmic differences observed for diagnosis and type of treatment are indicative of a higher circadian rhythmicity robustness in SUD and therapeutic community patients as compared to SUD-MDD and ambulatory ones, respectively. Although drug consumption exerts a negative effect on the circadian rhythmicity, our results (high amplitude and rhythm stability) are indicative of an adequate circadian functioning as well as of an adjustment to the light-dark cycle in both diagnosis and type of treatment which may constitute a marker of the adherence to treatment and recovery status.