How stepping out helped us tune in: finding space and time to as an early career researcher.

The transition from postdoc to junior faculty is exciting and uniquely challenging. On one hand, it allows for increased creative freedom and the opportunity to grow into an independent scientist. On the other hand, it comes with increasing administrative responsibilities, feelings of isolation, and high pressure to perform.

Aversion to light is associated with impulsivity.

Exposure to bright light can be visually aversive. This study explored the association between light aversion and various facets of impulsivity. A total of 1,245 participants completed the UPPS-Impulsive Behavior Scale to assess five facets of impulsivity.

ENLIGHT: A consensus checklist for reporting laboratory-based studies on the non-visual effects of light in humans.

Background: There is no consensus on reporting light characteristics in studies investigating non-visual responses to light. This project aimed to develop a reporting checklist for laboratory-based investigations on the impact of light on non-visual physiology.

Methods: A four-step modified Delphi process (three questionnaire-based feedback rounds and one face-to-face group discussion) involving international experts was conducted to reach consensus on the items to be included in the checklist.

Wearable light spectral sensor optimized for measuring daily α-opic light exposure.

Light has many non-visual effects on human physiology, including alterations in sleep, mood, and alertness. These effects are mainly mediated by photoreceptors containing the photopigment melanopsin, which has a peak sensitivity to short wavelength ('blue') light. Commercially available light sensors are commonly wrist-worn and report photopic illuminance and are calibrated to perceive visual brightness and hence cannot be used to investigate the non-visual impacts of light.

Afraid of the dark: Light acutely suppresses activity in the human amygdala.

Light improves mood. The amygdala plays a critical role in regulating emotion, including fear-related responses. In rodents the amygdala receives direct light input from the retina, and light may play a role in fear-related learning.

Attitudes Towards Sleep as a Time Commitment are Associated with Sleep Regularity.

: Irregular sleep-wake patterns are associated with poor health outcomes. However, factors that lead individuals to adopt more regular sleep-wake patterns are not well understood. This study aimed to (i) examine the relationship between sleep regularity and attitudes toward sleep in undergraduates; (ii) test an intervention to improve sleep regularity based on personalized feedback; and (iii) investigate whether changes in attitudes toward sleep associate with improved sleep regularity.

Evening home lighting adversely impacts the circadian system and sleep.

The regular rise and fall of the sun resulted in the development of 24-h rhythms in virtually all organisms. In an evolutionary heartbeat, humans have taken control of their light environment with electric light. Humans are highly sensitive to light, yet most people now use light until bedtime.

Accuracy of the GENEActiv Device for Measuring Light Exposure in Sleep and Circadian Research.

Light is a variable of key interest in circadian rhythms research, commonly measured using wrist-worn sensors. The GENEActiv Original is a cost-effective and practical option for assessing light in ambulatory settings. With increasing research on health and well-being incorporating sleep and circadian factors, the validity of wearable devices for assessing light environments needs to be evaluated.

The Role of Light Sensitivity and Intrinsic Circadian Period in Predicting Individual Circadian Timing.

There is large interindividual variability in circadian timing, which is underestimated by mathematical models of the circadian clock. Interindividual differences in timing have traditionally been modeled by changing the intrinsic circadian period, but recent findings reveal an additional potential source of variability: large interindividual differences in light sensitivity. Using an established model of the human circadian clock with real-world light recordings, we investigated whether changes in light sensitivity parameters or intrinsic circadian period could capture variability in circadian timing between and within individuals.

Sleep and circadian instability in delayed sleep-wake phase disorder.

Study Objectives: In patients with delayed sleep-wake phase disorder (DSWPD), the circadian clock may be more easily affected by light at night. This creates a potential vulnerability, whereby individuals with irregular schedules may have less stable circadian rhythms. We investigated the stability of circadian timing and regularity of sleep in patients with DSWPD and healthy controls.

Advanced melatonin onset relative to sleep in women with unmedicated major depressive disorder.

Studies on circadian timing in depression have produced variable results, with some investigations suggesting phase advances and others phase delays. This variability may be attributable to differences in participant diagnosis, medication use, and methodology between studies. This study examined circadian timing in a sample of unmedicated women with and without unipolar major depressive disorder.

High sensitivity and interindividual variability in the response of the human circadian system to evening light.

Before the invention of electric lighting, humans were primarily exposed to intense (>300 lux) or dim (<30 lux) environmental light-stimuli at extreme ends of the circadian system's dose-response curve to light. Today, humans spend hours per day exposed to intermediate light intensities (30-300 lux), particularly in the evening. Interindividual differences in sensitivity to evening light in this intensity range could therefore represent a source of vulnerability to circadian disruption by modern lighting.

Traits related to bipolar disorder are associated with an increased post-illumination pupil response.

Mood states in bipolar disorder appear to be closely linked to changes in sleep and circadian function. It has been suggested that hypersensitivity of the circadian system to light may be a trait vulnerability for bipolar disorder. Healthy persons with emotional-behavioural traits associated with bipolar disorder also appear to exhibit problems with circadian rhythms, which may be associated with individual differences in light sensitivity.

Imaging Individual Differences in the Response of the Human Suprachiasmatic Area to Light.

Circadian disruption is associated with poor health outcomes, including sleep and mood disorders. The suprachiasmatic nucleus (SCN) of the anterior hypothalamus acts as the master biological clock in mammals, regulating circadian rhythms throughout the body. The clock is synchronized to the day/night cycle via retinal light exposure.

Increased sensitivity of the circadian system to light in delayed sleep-wake phase disorder.

Key Points: This is the first study to demonstrate an altered circadian phase shifting response in a circadian rhythm sleep disorder. Patients with delayed sleep-wake phase disorder (DSWPD) demonstrate greater sensitivity of the circadian system to the phase-delaying effects of light. Increased circadian sensitivity to light is associated with later circadian timing within both control and DSWPD groups.

The pupillary light reflex distinguishes between circadian and non-circadian delayed sleep phase disorder (DSPD) phenotypes in young adults.

This study investigated the utility of the pupillary light reflex as a method of differentiating DSPD patients with delayed melatonin timing relative to desired/required sleep time (circadian type) and those with non-delayed melatonin timing (non-circadian type). All participants were young adults, with a total of 14 circadian DSPD patients (M = 28.14, SD = 5.