Preliminary findings on the influence of the presence of others' eyes on food intake.

Background: The presence of others' eyes has been shown to influence food evaluation. Aim: The purpose of the present study was to investigate whether the presence of others' gaze would lead to a reduction in food intake in accordance with social norms. Methods: In this study, we enlisted the participation of 30 volunteers. During the experiment, participants had the opportunity to consume noodles freely as much as they wanted while viewing one of the three images: (1) featuring a person with open eyes (Open condition), (2) depicting a person with closed eyes (Closed condition), and (3) displaying an image devoid of a person (None condition). Results: Food consumption in each condition was 460.00 ± 20.97 g for the Open condition, 515.57 ± 22.97 g in the Closed condition, and 505.03 ± 21.05 g in None condition. The condition had a statistically significant main effect (F = 4.656, p = .013). The Least-Square means analysis revealed that food consumption in the Open condition was significantly lower than in the other two conditions (Closed and None conditions) (Closed - Open: t = 2.872 [95% CI: 16.844-94.289], p = .006; None - Open: t = 2.328 [95% CI: 6.311-83.756], p = .023). There was no significant difference in food consumption between the Closed and None conditions (Closed - None: t = 0.545 [95% CI: -28.189-49.256], p = .588). Conclusion: The results of the present study suggest that the presence of others' eyes would reduce food intake in accordance with social norms.

GWAS of folate metabolism with gene-environment interaction analysis revealed the possible role of lifestyles in the control of blood folate metabolites in Japanese - the J-MICC Study.

BACKGROUND: The present genome-wide association study (GWAS) aimed to reveal the genetic loci associated with folate metabolites as well as to detect related gene-environment interactions in Japanese. METHODS: We conducted the GWAS of plasma homocysteine (Hcy), folic acid (FA), and vitamin B12 (VB12) levels in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study participants who joined from 2005 to 2012, and also estimated gene-environment interactions. In the replication phase, we used data from the Yakumo Study conducted in 2009. In the discovery phase, data of 2,263 participants from four independent study sites of the J-MICC Study were analyzed. In the replication phase, data of 573 participants from the Yakumo Study were analyzed. RESULTS: For Hcy, MTHFR locus on chr 1, NOX4 on chr 11, CHMP1A on chr 16, and DPEP1 on chr 16 reached genome-wide significance (P < 5×10-8). MTHFR also associated with FA, and FUT2 on chr 19 associated with VB12. We investigated gene-environment interactions in both studies and found significant interactions between MTHFR C677T and ever drinking, current drinking, and physical activity > 33% on Hcy (ß = 0.039, 0.038 and -0.054, P = 0.018, 0.021 and < 0.001, respectively) and the interaction of MTHFR C677T with ever drinking on FA (ß = 0.033, P = 0.048). CONCLUSIONS: The present GWAS revealed the folate metabolism-associated genetic loci and gene-environment interactions with drinking and physical activity in Japanese, suggesting the possibility of future personalized CVD prevention.

Association between awareness of limiting food intake and all-cause mortality: A cohort study in Japan.

BACKGROUND: Improving diets requires an awareness of the need to limit foods for which excessive consumption is a health problem. Since there are limited reports on the link between this awareness and mortality risk, we examined the association between awareness of limiting food intake (energy, fat, and sweets) and all-cause mortality in a Japanese cohort study. METHODS: Participants comprised 58,772 residents (27,294 men; 31,478 women) aged 35-69 years who completed baseline surveys of the Japan Multi-Institutional Collaborative Cohort Study from 2004 to 2014. Hazard ratios (HRs) for all-cause mortality and 95% confidence intervals (CIs) were estimated by sex using a Cox proportional hazard model, with adjustment for related factors. Mediation analysis with fat intake as a mediator was also conducted. RESULTS: The mean follow-up period was 11 years and 2,516 people died. Estimated energy and fat intakes according to the Food Frequency Questionnaire were lower in those with awareness of limiting food intake than in those without this awareness. Women with awareness of limiting fat intake showed a significant decrease in mortality risk (HR=0.73; 95% CI, 0.55 to 0.94). Mediation analysis revealed that this association was due to the direct effect of the awareness of limiting fat intake and that the total effect was not mediated by actual fat intake. Awareness of limiting energy or sweets intake was not related to mortality risk reduction. CONCLUSION: Awareness of limiting food intake had a limited effect on reducing all-cause mortality risk.

The effect of background music tempo on eating speed and food intake volume within in healthy women.

BACKGROUND: The effects of the different tempos of background music (BGM) on food intake and eating speed have not been fully studied. AIM: The study aimed to investigate the influence of changing the tempo of BGM during meals on food intake and to explore strategies to support appropriate eating behavior. METHODS: Twenty-six healthy young adult women participated in this study. In the experimental phase, each participant ate a meal under three separate conditions: fast (120% speed), moderate (original, 100% speed), and slow (80% speed) BGM. The same music was used for each condition, and appetite before and after eating, the amount of food consumed, and eating speed were recorded. RESULTS: The results showed that food intake (g, mean ± standard error (SE)) was slow: 317.9 ± 22.2, moderate: 400.7 ± 16.0, and fast: 342.9 ± 22.0. Eating speed (g/s, mean ± SE) was slow: 28.1 ± 2.8, moderate: 34.2 ± 2.7, and fast: 27.2 ± 2.4. The analysis showed that the moderate condition showed greater speed than the fast and slow conditions (slow-fast: p = .008; moderate-slow: p = .012; moderate-fast: p = .004). Moreover, the food intake in the moderate condition was significantly higher than that in the slow and fast conditions (moderate-slow: p < .001; moderate-fast: p < .001), and there was no significant difference between the slow and fast conditions in this regard (p = .077). CONCLUSION: These results suggest that original tempo BGM led to higher food intake compared to the faster and slower tempo conditions. These findings suggest that listening to music at an original tempo during meals may support appropriate eating behavior.

Effects of transcutaneous electrical nerve stimulation and visuotactile synchrony on the embodiment of an artificial hand.

The rubber hand illusion (RHI) is an experimental paradigm known to produce a bodily illusion. Transcutaneous electrical nerve stimulation (TENS) combined with the RHI induces a stronger illusion than the RHI alone. Visuotactile stimulus synchrony is an important aspect of the RHI. However, the effect of TENS and visuotactile stimulus synchrony in TENS combined with the RHI remains unknown. The purpose of this study was to investigate the effects of TENS and visuotactile stimulus synchrony on the embodiment of an artificial hand when using TENS combined with the RHI. The participants underwent four experimental conditions in random order: TENS/noTENS × Synchronous/Asynchronous. TENS was set at an intensity such that it generated a feeling of electrical paresthesia in the radial nerve area of the hand but did not cause pain, i.e., 100-Hz pulse frequency, 80-µs pulse duration, and a constant pulse pattern. A visuotactile stimulus, either temporally synchronous or asynchronous, was generated using paintbrush strokes. To evaluate the outcome measures, the participants completed a questionnaire report and proprioceptive drift assessments (motor response and perceptual response). There were significant main effects of TENS and visuotactile synchrony, but no interaction between these factors, on the results of the questionnaire and the perceptual response. In contrast, there was no significant effect on the result of the motor response. These findings indicate that TENS and visuotactile synchrony might affect differently the embodiment of an artificial hand when using TENS combined with the RHI.

Molecular aspects of flower senescence and strategies to improve flower longevity.

Flower longevity is one of the most important traits for ornamental plants. Ethylene plays a crucial role in flower senescence in some plant species. In several species that show ethylene-dependent flower senescence, genetic modification targeting genes for ethylene biosynthesis or signaling has improved flower longevity. Although little is known about regulatory mechanisms of petal senescence in flowers that show ethylene-independent senescence, a recent study of Japanese morning glory revealed that a NAC transcription factor, EPHEMERAL1 (EPH1), is a key regulator in ethylene-independent petal senescence. EPH1 is induced in an age-dependent manner irrespective of ethylene signal, and suppression of EPH1 expression dramatically delays petal senescence. In ethylene-dependent petal senescence, comprehensive transcriptome analyses revealed the involvement of transcription factors, a basic helix-loop-helix protein and a homeodomain-leucine zipper protein, in the transcriptional regulation of the ethylene biosynthesis enzymes. This review summarizes molecular aspects of flower senescence and discusses strategies to improve flower longevity by molecular breeding.

Morphological changes in senescing petal cells and the regulatory mechanism of petal senescence.

Petal senescence, or programmed cell death (PCD) in petals, is a developmentally regulated and genetically programmed process. During petal senescence, petal cells show morphological changes associated with PCD: tonoplast rupture and rapid destruction of the cytoplasm. This type of PCD is classified as vacuolar cell death or autolytic PCD based on morphological criteria. In PCD of petal cells, characteristic morphological features including an autophagy-like process, chromatin condensation, and nuclear fragmentation are also observed. While the phytohormone ethylene is known to play a crucial role in petal senescence in some plant species, little is known about the early regulation of ethylene-independent petal senescence. Recently, a NAC (NAM/ATAF1,2/CUC2) transcription factor was reported to control the progression of PCD during petal senescence in Japanese morning glory, which shows ethylene-independent petal senescence. In ethylene-dependent petal senescence, functional analyses of transcription factor genes have revealed the involvement of a basic helix-loop-helix protein and a homeodomain-leucine zipper protein in the transcriptional regulation of the ethylene biosynthesis pathway. Here we review the recent advances in our knowledge of petal senescence, mostly focusing on the morphology of senescing petal cells and the regulatory mechanisms of PCD by senescence-associated transcription factors during petal senescence.

Complementary activation of the ipsilateral primary motor cortex during a sustained handgrip task.

PURPOSE: Near-infrared spectroscopy (NIRS) can be used to examine bilateral motor cortex activation during a sustained motor task in brain areas where increased oxygenation reflects cortical activation. This study examines the time course of activation of the bilateral motor cortex during a moderate-intensity handgrip task. METHODS: Ten healthy right-handed male subjects participated in this study. Functional NIRS probes were placed over the cortex to measure motor cortical activations while the subjects performed a 180-s handgrip task incrementally [30-60% of the maximal voluntary contraction (MVC) at 0.17% increase/s] RESULTS: Contralateral primary motor cortex (ContraM1) oxygenation values significantly increased from baseline between 40 and 120 s after the start of the motor task (p < 0.05). Moreover, the ipsilateral primary motor cortex (IpsiM1) oxygenation values significantly increased from baseline between 140 and 180 s after the start of the motor task (p < 0.05). IpsiM1 oxygenation gradually increased from 140 to 180 s, whereas ContraM1 oxygenation gradually decreased from 120 to 180 s after the start of the motor task. CONCLUSION: These results suggest that the complementary functions of IpsiM1 become activated in response to the working of the ContraM1 during a continuous handgrip task.

Identification of a NAC transcription factor, EPHEMERAL1, that controls petal senescence in Japanese morning glory.

In flowering plants, floral longevity is species-specific and is closely linked to reproductive strategy; petal senescence, a type of programmed cell death (PCD), is a highly regulated developmental process. However, little is known about regulatory pathways for cell death in petal senescence, which is developmentally controlled in an age-dependent manner. Here, we show that a NAC transcription factor, designated EPHEMERAL1 (EPH1), positively regulates PCD during petal senescence in the ephemeral flowers of Japanese morning glory (Ipomoea nil). EPH1 expression is induced independently of ethylene signaling, and suppression of EPH1 resulted in Japanese morning glory flowers that are in bloom until the second day. The suppressed expression of EPH1 delays progression of PCD, possibly through suppression of the expression of PCD-related genes, including genes for plant caspase and autophagy in the petals. Our data further suggest that EPH1 is involved in the regulation of ethylene-accelerated petal senescence. In this study, we identified a key regulator of PCD in petal senescence, which will facilitate further elucidation of the regulatory network of petal senescence.

Sleep duration has a limited impact on the prevalence of menstrual irregularities in athletes: a cross-sectional study.

Background: This study aimed to investigate the relationship between the prevalence of menstrual irregularities, energy intake, and sleep deprivation among female athletes. Methods: A total of 128 female athletes, with an average age of 19.2 ± 1.2 years, participated in the study and tracked their food intake over a three-day period. Menstrual status and sleep duration were assessed using a questionnaire, and psychological anxiety was evaluated using the State and Trait Anxiety Inventory (STAI). These were measured once during the investigation. The impact of sleep status on state anxiety and daily energy intake was examined using the T-test. A generalized linear model (GLM) with a log link function was employed to investigate the effects of sleep deprivation on the presence of menstrual irregularities. Results: As the results of the present study, sleep deprivation significant increased both state and trait anxiety (p < 0.05), as well as affecting energy intake (p < 0.05), particularly protein and carbohydrate intakes (p < 0.05). However, GLM analysis indicated that while sleep deprivation did not directly influence the prevalence of menstrual irregularities (p > 0.05), state anxiety emerged as a significant factor impacting the prevalence of menstrual irregularities (p < 0.05). Conclusions: The results of the present study suggest a potential pathway wherein sleep deprivation might elevate state anxiety levels, consequently indirectly contributing to an increase the probability of menstrual irregularities. In conclusion, the results of the presents study provide novels insights suggesting that sleep deprivation might directly increase state anxiety and indirectly affect the prevalence of menstrual irregularities. Hence, decreased sleep duration might be related to mental health issues and the prevalence of menstrual irregularities both significant concerns among female athletes. Future studies will play a crucial role in further elucidating how sleep patterns impact the health and well-being of female athletes.

A chemical approach to extend flower longevity of Japanese morning glory via inhibition of master senescence regulator EPHEMERAL1.

Petal senescence in flowering plants is a type of programmed cell death with highly regulated onset and progression. A NAM/ATAF1,2/CUC2 transcription factor, EPHEMERAL1 (EPH1), has been identified as a key regulator of petal senescence in Japanese morning glory (Ipomoea nil). Here we used a novel chemical approach to delay petal senescence in Japanese morning glory by inhibiting the DNA-binding activity of EPH1. A cell-free high-throughput screening system and subsequent bioassays found two tetrafluorophthalimide-based compounds, Everlastin1 and Everlastin2, that inhibited the EPH1-DNA interaction and delayed petal senescence. The inhibitory mechanism was due to the suppression of EPH1 dimerization. RNA-sequencing analysis revealed that the chemical treatment strongly suppressed the expression of programmed cell death- and autophagy-related genes. These results suggest that a chemical approach targeting a transcription factor can regulate petal senescence.

Pollination induces autophagy in petunia petals via ethylene.

Autophagy is one of the main mechanisms of degradation and remobilization of macromolecules, and it appears to play an important role in petal senescence. However, little is known about the regulatory mechanisms of autophagy in petal senescence. Autophagic processes were observed by electron microscopy and monodansylcadaverine staining of senescing petals of petunia (Petunia hybrida); autophagy-related gene 8 (ATG8) homologues were isolated from petunia and the regulation of expression was analysed. Nutrient remobilization was also examined during pollination-induced petal senescence. Active autophagic processes were observed in the mesophyll cells of senescing petunia petals. Pollination induced the expression of PhATG8 homologues and was accompanied by an increase in ethylene production. Ethylene inhibitor treatment in pollinated flowers delayed the induction of PhATG8 homologues, and ethylene treatment rapidly upregulated PhATG8 homologues in petunia petals. Dry weight and nitrogen content were decreased in the petals and increased in the ovaries after pollination in detached flowers. These results indicated that pollination induces autophagy and that ethylene is a key regulator of autophagy in petal senescence of petunia. The data also demonstrated the translocation of nutrients from the petals to the ovaries during pollination-induced petal senescence.

Exploring the relationship between nutritional intake and menstrual cycle in elite female athletes.

This study aimed to examine potential variations in nutritional intake among female athletes, including top-level, throughout the menstrual cycle. A total 122 female athletes participated in the study, documenting their food consumption over a 3-day period. The menstrual status of female athletes was also assessed, and using the survey results, the phase of the menstrual cycle (the follicular, early luteal, or late luteal) during which each meal was recorded was determined. Consequently, the meal records were categorized into the respective three phases. The findings of this study indicated that there were no notable disparities in nutritional intake, encompassing energy, protein, fat, carbohydrate, calcium, iron, and fiber, across the three phases of the menstrual cycle. The results imply that female athletes may experience comparatively smaller variations in nutrient intake related to the menstrual cycle. This could be attributed to the higher energy requirements of female athletes because of their rigorous training. This study underscores the significance of accounting for the population when examining nutrient intake changes associated with the menstrual cycle.

Cross-modal and subliminal effects of smell and color.

In the present study, we examined whether the cross-modal effect can be obtained between odors and colors, which has been confirmed under olfactory recognizable conditions and also occurs under unrecognizable conditions. We used two flavors of red fruits such as strawberries and tomatoes for this purpose. We also aimed to compare whether similar cross-modal effects could be achieved by setting the flavors at recognizable (liminal) and unrecognizable (subliminal) concentrations in the experiment. One flavor at a normal concentration (0.1%, Liminal condition) and one at a concentration below the subliminal threshold (0.015%, Subliminal condition), were presented, and the color that resembled the smell most closely from among the 10 colors, was selected by participants. Except for the subliminal tomato condition, each odor was significantly associated with at least one color (p < 0.01). Participants selected pink and red for liminal strawberry (0.1%) (p < 0.05), pink for subliminal strawberry (0.015%) (p < 0.05), and orange for liminal tomato (0.1%) (p < 0.05), but there was no color selected for subliminal tomato (0.015%) (p < 0.05). The results of this study suggest that the flavor of tomato produced a cross-modal effect in liminal conditions, but not in subliminal conditions. On the other hand, the results of the present study suggest that the flavor of strawberries produces a cross-modal effect even under subliminal conditions. This study showed that cross-modal effects might exist, even at unrecognizable levels of flavor.

Effects of different food hardness on cognitive inhibitory control function.

Mastication leads to an immediate enhancement in cognitive functions, including inhibitory control. Furthermore, the hardness of the food increases sympathetic nerve activity during and immediately after mastication. Hence, the cognitive function could be enhanced by increased sympathetic nerve activity. The present study aimed to investigate the effects of food hardness on cognitive inhibitory control function in humans. The participants were 23 healthy adults (19-22 years old). Experiments were conducted with two types of gummies (soft and hard). The participants ingested 13 g of gummies and performed a stop-signal task to measure cognitive inhibitory control function after they rested for 5 min. The reaction time for the stop-signal task after gummy consumption was significantly shorter in the hard gummy condition compared to the soft gummy condition (p < .05). Furthermore, the accuracy rate of the responses was also significantly higher in the hard gummy condition compared to the soft gummy condition (p < .05). The results of the present study suggest that food hardness enhances cognitive inhibitory control function in humans.

RNA-directed DNA methylation induces transcriptional activation in plants.

A class-C floral homeotic gene of Petunia, pMADS3, is specifically expressed in the stamen and carpels of developing flowers. We had previously reported the ect-pMADS3 phenomenon in which introduction of a part of the pMADS3 genomic sequence, including intron 2, induces ectopic expression of endogenous pMADS3. Unlike transcriptional or posttranscriptional gene silencing triggered by the introduction of homologous sequences, this observation is unique in that the gene expression is up-regulated. In this study, we demonstrated that the ect-pMADS3 phenomenon is due to transcriptional activation based on RNA-directed DNA methylation (RdDM) occurring in a particular CG in a putative cis-element in pMADS3 intron 2. The CG methylation was maintained over generations, along with pMADS3 ectopic expression, even in the absence of RNA triggers. These results demonstrate a previously undescribed transcriptional regulatory mechanism that could lead to the generation of a transcriptionally active epiallele, thereby contributing to plant evolution. Our results also reveal a putative negative cis-element for organ-specific transcriptional regulation of class-C floral homeotic genes, which could be difficult to identify by other approaches.

Time course changes in corticospinal excitability during repetitive peripheral magnetic stimulation combined with motor imagery.

Repetitive peripheral magnetic stimulation (rPMS) induces proprioceptive afferents and facilitates corticospinal excitability. Short-term sessions of rPMS combined with motor imagery (MI) enhance corticospinal excitability more than rPMS alone. However, it is not clear how long the intervention of rPMS combined with MI would be needed to facilitate corticospinal excitability. Therefore, we investigated the time course change in corticospinal excitability during the combination of rPMS and MI. Thirteen healthy volunteers participated in a 20-min intervention under the following three experimental conditions on different days: rPMS, MI, and rPMS combined with MI (rPMS + MI). In the rPMS and rPMS + MI, the participants were delivered rPMS, which was 25 Hz, 2 s/train at 1.5 × of the train intensity induced muscle contractions, through the wrist extensor muscles. In the MI and rPMS + MI, the participants repeatedly imagined wrist movements for 2 s. Motor evoked potentials (MEPs) were recorded from the extensor carpi radialis (ECR) and flexor carpi radialis (FCR) muscles every 5 min for each condition. The MEP amplitudes of the ECR after > 10 min of intermittent rPMS combined with MI were greater than baseline. The MEP amplitude of the ECR in rPMS + MI was greater than that in rPMS condition after 20 min of intervention. The present results suggest that over 10 min of intermittent rPMS combined with MI facilitates corticospinal excitability, and that the effect of rPMS combined with MI on corticospinal excitability might be greater than that of rPMS alone.

Increased vitamin D intake may reduce psychological anxiety and the incidence of menstrual irregularities in female athletes.

Background: Vitamin D deficiency has been associated with major depression and premenstrual mood symptoms, and menstrual irregularity has been correlated with mental anxiety. However, the potential effect of increased vitamin D intake on reducing the risk of menstrual irregularities by decreasing psychological anxiety is yet to be fully elucidated. The existence of such a relationship in athletes with high levels of psychological anxiety and adequate dietary intake remains unknown. Therefore, this study aimed to examine the effects of vitamin D intake on psychological anxiety levels and the risk of menstrual irregularities in healthy college-and international-level female athletes. Methods: Female intercollege-level track and field and international-level rowing athletes (n = 107) aged 15-24 years were included in this study. Their nutritional intake, body mass, body fat, mental anxiety, and menstrual irregularities were investigated. A generalized linear mixed model (GLMM) was used to examine the effects of several parameters on menstrual irregularities. The independent variables introduced into the GLMM were determined based on Akaike's information criterion. Results: The GLMM identified a significant interaction effect of vitamin D intake and state anxiety on menstrual irregularities, with a p-value of 0.049 and an odds ratio of 0.423. The study results suggest that increased vitamin D intake in relatively young endurance athletes may reduce mental anxiety, consequently decreasing menstrual irregularities.

Effects of Repetitive Peripheral Magnetic Stimulation through Hand Splint Materials on Induced Movement and Corticospinal Excitability in Healthy Participants.

Repetitive peripheral magnetic stimulation (rPMS) is a non-invasive neuromodulation technique. Magnetic fields induced by rPMS pass through almost all materials, and it has clinical applications for neurorehabilitation. However, the effects of rPMS through clothing and orthosis on induced movement and corticospinal excitability remain unclear. The aim of this study was to determine whether rPMS induces movement and enhances corticospinal excitability through hand splint materials. rPMS was applied directly to the skin (L0) and through one (L1) or two (L2) layers of splint material in 14 healthy participants at 25-Hz, 2-s train per 6 s for a total of 20 min. rPMS was delivered to the forearm with the stimulus intensity set to 1.5-times the train intensity-induced muscle contractions under the L0 condition. We recorded induced wrist movements during rPMS and motor-evoked potentials of the extensor carpi radialis pre- and post-application. The results showed that rPMS induced wrist movements in L0 and L1, and it facilitated corticospinal excitability in L0 but not in L1 and L2. This suggests that rPMS can make electromagnetic induction on periphery even when applied over clothing and orthosis and demonstrates the potential clinical applications of this technique for neurorehabilitation.

Irregular sleep and all-cause mortality: A large prospective cohort study.

OBJECTIVES: Previous studies using objective parameters have shown that irregular sleep is associated with the disease incidence, progression, or mortality. This study aimed to determine the association between subjective sleep duration and sleep regularity, with mortality in a large population. METHODS: Participants were from the Japan Multi-Institutional Collaborative Cohort study. We obtained information from each participant on sleep duration, sleep regularity, and demographics and overall lifestyle using self-administered questionnaires. We defined sleep regularity according to participants' subjective assessment of sleep/wake time regularity. Participants (n = 81,382, mean age: 58.1 ± 9.1years, males: 44.2%) were classified into 6 groups according to sleep duration and sleep regularity. Hazard ratios (HR) for time-to-event of death were calculated using the Cox proportional hazards model. RESULTS: The mean follow-up period was 9.1 years and the mean sleep duration was 6.6 h/day. Irregular sleep significantly increased the risk of all-cause mortality in all models compared with regular sleep (HR 1.30, 95% confidence interval; CI, 1.18-1.44), regardless of sleep duration. Multivariable analysis of the 6 groups by sleep pattern (sleep regularity and duration) showed irregular sleep and sleep durations of <6 h/day, 6 to <8 h/day, or ≥8 h/day were associated with a 1.2-1.5-fold increases in mortality, compared to regular sleep and sleep duration of 6 to <8 h/day. CONCLUSIONS: Our study shows an association between sleep irregularity and all-cause mortality in a large Japanese population. Our findings provide further confirmation of the need to consider not only sleep duration, but also the regularity aspect of sleep schedules.