The impact of structured sleep schedules prior to an in-laboratory study: Individual differences in sleep and circadian timing.

INTRODUCTION: Many sleep and circadian studies require participants to adhere to structured sleep-wake schedules designed to stabilize sleep outcomes and circadian phase prior to in-laboratory testing. The effectiveness of this approach has not been rigorously evaluated, however. We therefore investigated the differences between participants' unstructured and structured sleep over a three-week interval. METHODS: Twenty-three healthy young adults completed three weeks of sleep monitoring, including one week of unstructured sleep and two weeks of structured sleep with consistent bed and wake times. Circadian phase was assessed via salivary dim light melatonin onset (DLMO) during both the unstructured and structured sleep episodes. RESULTS: Compared to their unstructured sleep schedule, participants' bed- and wake times were significantly earlier in their structured sleep, by 34 ± 44 mins (M ± SD) and 44 ± 41 mins, respectively. During structured sleep, circadian phase was earlier in 65% of participants (40 ± 32 mins) and was later in 35% (41 ± 25 mins) compared to unstructured sleep but did not change at the group level. While structured sleep reduced night-to-night variability in sleep timing and sleep duration, and improved the alignment (phase angle) between sleep onset and circadian phase in the most poorly aligned individuals (DLMO < 1h or > 3h before sleep onset time; 25% of our sample), sleep duration and quality were unchanged. CONCLUSION: Our results show adherence to a structured sleep schedule results in more regular sleep timing, and improved alignment between sleep and circadian timing for those individuals who previously had poorer alignment. Our findings support the use of structured sleep schedules prior to in-laboratory sleep and circadian studies to stabilize sleep and circadian timing in healthy volunteers.

More than depression: a multi-dimensional assessment of postpartum distress symptoms before and after a residential early parenting program.

INTRODUCTION: Parents are vulnerable to psychological distress symptoms in the postpartum period. It is routine to screen for depressive symptoms, but anxiety, stress, fatigue, irritability and insomnia symptoms are less often assessed despite their prevalence. This study aimed to assess multiple dimensions of psychological distress, and their reliable change and clinically significant change among women admitted to a residential program for assistance with unsettled infant behaviors (UIB). METHOD: Women admitted to a five-night residential early parenting program completed self-report measures: the Depression Anxiety Stress Scale, Irritability Depression Anxiety Scale, Fatigue Severity Scale, and Insomnia Severity Index. A sub-group completed a computerized emotional Go-NoGo (EGNG) task as a measure of emotional impulsivity. RESULTS: Seventy-eight women were recruited (Mage = 34.46, SDage = 4.16). On admission, 48% of women reported clinically elevated depressive symptoms and 97.5% of women not reporting elevated depressive symptoms reported clinical elevations in at least one other form of distress. Upon discharge, all self-report distress symptoms were significantly reduced (all p-values <.001), but reliable and clinically significant change only occurred in a subgroup of women. There were no significant changes in indicators of impulsivity based on the EGNG. CONCLUSIONS: In addition to, and often in the absence of, depressive symptoms, women attending an early parenting program experienced a wide range of psychological distress, including fatigue, insomnia, anxiety and stress. Different forms of distress improved in different magnitudes to the treatment provided. These findings highlight the need for a multi-dimensional approach in the assessment and treatment of postpartum distress.

Impact of Common Diabetes Risk Variant in MTNR1B on Sleep, Circadian, and Melatonin Physiology.

The risk of type 2 diabetes (T2D) is increased by abnormalities in sleep quantity and quality, circadian alignment, and melatonin regulation. A common genetic variant in a receptor for the circadian-regulated hormone melatonin (MTNR1B) is associated with increased fasting blood glucose and risk of T2D, but whether sleep or circadian disruption mediates this risk is unknown. We aimed to test if MTNR1B diabetes risk variant rs10830963 associates with measures of sleep or circadian physiology in intensive in-laboratory protocols (n = 58-96) or cross-sectional studies with sleep quantity and quality and timing measures from self-report (n = 4,307-10,332), actigraphy (n = 1,513), or polysomnography (n = 3,021). In the in-laboratory studies, we found a significant association with a substantially longer duration of elevated melatonin levels (41 min) and delayed circadian phase of dim-light melatonin offset (1.37 h), partially mediated through delayed offset of melatonin synthesis. Furthermore, increased T2D risk in MTNR1B risk allele carriers was more pronounced in early risers versus late risers as determined by 7 days of actigraphy. Our results provide the surprising insight that the MTNR1B risk allele influences dynamics of melatonin secretion, generating a novel hypothesis that the MTNR1B risk allele may extend the duration of endogenous melatonin production later into the morning and that early waking may magnify the diabetes risk conferred by the risk allele.

Fatigue and the criminal law.

Fatigue is an increasingly recognised risk factor for transportation accidents. In light of this, there is the question of whether driving whilst fatigued should be a criminal offence. This paper discusses the current legal position, including the problems of voluntary conduct and self awareness. Three models for reform are proposed. The manner in which scientific research can inform legal consideration and future directions for research are discussed.