This study quantifies sex differences in the diurnal and circadian variation of sleep and waking while controlling for menstrual cycle phase and hormonal contraceptive use. We compared the diurnal and circadian variation of sleep and alertness of 8 women studied during two phases of the menstrual cycle and 3 women studied during their midfollicular phase with that of 15 men. Participants underwent an ultradian sleep-wake cycle (USW) procedure consisting of 36 cycles of 60-min wake episodes alternating with 60-min nap opportunities. Core body temperature (CBT), salivary melatonin, subjective alertness, and polysomnographically recorded sleep were measured throughout this procedure. All analyzed measures showed a significant diurnal and circadian variation throughout the USW procedure. Compared with men, women demonstrated a significant phase advance of the CBT but not melatonin rhythms, as well as an advance in the diurnal and circadian variation of sleep measures and subjective alertness. Furthermore, women experienced an increased amplitude of the diurnal and circadian variation of alertness, mainly due to a larger decline in the nocturnal nadir. Our results indicate that women are likely initiating sleep at a later circadian phase than men, which may be one factor contributing to the increased susceptibility to sleep disturbances reported in women. Lower nighttime alertness is also observed, suggesting a physiological basis for a greater susceptibility to maladaptation to night shift work in women.sex difference | circadian variation of sleep | circadian variation of alertness | core body temperature | melatonin A meta-analysis has indicated an overall increased risk ratio of 1.41 in women vs. men for experiencing insomnia, and this risk ratio increases to 1.64 when considering high-quality studies with rigorous methodology (1). The etiology of sex-based differences in vulnerability to sleep disturbances remains to be fully elucidated, but evidence points to a role for sex-based differences in sleep, its timing, and circadian rhythms as potential contributors (2).There is sufficient evidence to support a role for circadian factors in the pathophysiology of chronic insomnia, as the timing of sleep relative to the endogenous circadian system can substantially affect sleep initiation and maintenance (3). Interestingly, morphological differences, as well as variations in circulating hormones and their receptors, have been reported between sexes and can affect circadian physiology. For example, the localization of sex steroid receptors to the suprachiasmatic nucleus (SCN) and a sex difference in the expression of androgen and estrogen receptors there indicate a direct and differential role of specific gonadal steroid hormones in the circadian system (4). Moreover, a sexual dimorphism in structure and sex steroid receptor expression also exists in efferent targets of the SCN, including the preoptic area of the hypothalamus, which is known to influence sleep (4). In a recent postmortem brain study, the circadian vari...

Background: Kangaroo care (KC) has been widely using to improve the care of low birth weight infants. However, very little is known about cerebral hemodynamics responses in low birth weight infants during KC intervention. The objective of this study was to elucidate the response of cerebral hemodynamics during KC in low birth weight infants.

Background: Biological rhythmicity, particularly circadian rhythmicity, is considered to be a key mechanism in the maintenance of physiological function. Very little is known, however, about biological rhythmicity pattern in preterm and term neonates in neonatal intensive care units (NICU). In this study, we investigated whether term and preterm neonates admitted to NICU exhibit biological rhythmicity during the neonatal period.

The author-made SQ is a screening instrument comprised of 12 items to assess whether participants meet study inclusion criteria and do not meet any of the exclusion criteria. A specific item addressing co-sleeping is modelled conceptually on Ramos and colleagues' [63] study examining parental perceptions of sleep problems. The questionnaire requires approximately 5 minutes to complete. Eligibility Measures Behavioural Insomnia Questionnaire (BIQ)The BIQ is adapted by the authors based on the insomnia diagnosis criteria for children reported by Anders and Dahl [62]. The BIQ is comprised of 4 items to assess sleep onset disturbance and 4 items to assess night waking dyssomnia. An additional 9 items are included to capture sleep habits modelled from the ICSD-3/DSM-5 insomnia criteria. An evidence-based review [74] reported that the criteria, identified by Anders and Dahl, is one of few well-reported scales/assessments to evaluate insomnia symptoms in children. Only sleep onset items 1-4 are used to assess eligibility in this study. Children are determined to meet sleep onset disturbance criteria if two of the following three conditions are fulfilled for at least one month: 1) more than three parental reunions occur per night for children ages 12-14 months, or more than two reunions for children older than 24 months; 2) sleep onset latency is greater than 30 minutes for children ages 12-24 months, or greater than 20 minutes for children older than 24 months; and 3) parental presence is required for sleep onset for two or more nights per week. The BIQ requires approximately 5 minutes to complete. Pediatric Sleep Questionnaire (PSQ)The PSQ developed by Chervin and colleagues [64] is a 22-item questionnaire which measures features of the presence of pediatric sleep related breathing disorders (SRBD), including snoring, daytime sleepiness, and behavioural disturbance. Response options to each item are 1 "Yes," 0 "No," or excluded "Don't know." The PSQ includes 3 subscales: snoring (4 items), sleepiness (4 items), and inattentive/hyperactivity behaviour (6 items). Responses to all non-excluded items are averaged to obtain a total score between 0.00 and 1.00. Scores with a cut off value of 0.33 indicate the presence of an SRBD. The PSQ demonstrates strong association with diagnosis of an SRBD (P<0.0001); diagnosis is also reported to be strongly associated across the 3 subscales [74]. The PSQ has been validated for use in children aged 2-18 years, and yields a sensitivity of (α=.81-.85), a specificity of (α=.87) and correct diagnostic classification for 85-86% of subjects. It also demonstrates good internal consistency (α=.89) and good test-retest stability (r=.92) [63]. The average of the first 6 items of the PSQ related to snoring and sleep disrupted breathing are used to assess eligibility criteria in this study. A score of 0.33 and greater does not meet inclusion criteria. The PSQ requires approximately 5 minutes to complete.

The author-made SQ is a screening instrument comprised of 12 items to assess whether participants meet study inclusion criteria and do not meet any of the exclusion criteria. A specific item addressing co-sleeping is modelled conceptually on Ramos and colleagues' [63] study examining parental perceptions of sleep problems. The questionnaire requires approximately 5 minutes to complete. Eligibility Measures Behavioural Insomnia Questionnaire (BIQ)The BIQ is adapted by the authors based on the insomnia diagnosis criteria for children reported by Anders and Dahl [62]. The BIQ is comprised of 4 items to assess sleep onset disturbance and 4 items to assess night waking dyssomnia. An additional 9 items are included to capture sleep habits modelled from the ICSD-3/DSM-5 insomnia criteria. An evidence-based review [74] reported that the criteria, identified by Anders and Dahl, is one of few well-reported scales/assessments to evaluate insomnia symptoms in children. Only sleep onset items 1-4 are used to assess eligibility in this study. Children are determined to meet sleep onset disturbance criteria if two of the following three conditions are fulfilled for at least one month: 1) more than three parental reunions occur per night for children ages 12-14 months, or more than two reunions for children older than 24 months; 2) sleep onset latency is greater than 30 minutes for children ages 12-24 months, or greater than 20 minutes for children older than 24 months; and 3) parental presence is required for sleep onset for two or more nights per week. The BIQ requires approximately 5 minutes to complete. Pediatric Sleep Questionnaire (PSQ)The PSQ developed by Chervin and colleagues [64] is a 22-item questionnaire which measures features of the presence of pediatric sleep related breathing disorders (SRBD), including snoring, daytime sleepiness, and behavioural disturbance. Response options to each item are 1 "Yes," 0 "No," or excluded "Don't know." The PSQ includes 3 subscales: snoring (4 items), sleepiness (4 items), and inattentive/hyperactivity behaviour (6 items). Responses to all non-excluded items are averaged to obtain a total score between 0.00 and 1.00. Scores with a cut off value of 0.33 indicate the presence of an SRBD. The PSQ demonstrates strong association with diagnosis of an SRBD (P<0.0001); diagnosis is also reported to be strongly associated across the 3 subscales [74]. The PSQ has been validated for use in children aged 2-18 years, and yields a sensitivity of (α=.81-.85), a specificity of (α=.87) and correct diagnostic classification for 85-86% of subjects. It also demonstrates good internal consistency (α=.89) and good test-retest stability (r=.92) [63]. The average of the first 6 items of the PSQ related to snoring and sleep disrupted breathing are used to assess eligibility criteria in this study. A score of 0.33 and greater does not meet inclusion criteria. The PSQ requires approximately 5 minutes to complete.