Centre for Chronobiology

Seasonal Variation in the Responsiveness of the Melanopsin System to Evening Light: Why We Should Report Season When Collecting Data in Human Sleep and Circadian Studies Journal Article

Schöllhorn, I.; Stefani, O.; Blume, C.; Cajochen, C.

In: Clocks & Sleep, 2023.

@article{Schöllhorn2023b,

title = {Seasonal Variation in the Responsiveness of the Melanopsin System to Evening Light: Why We Should Report Season When Collecting Data in Human Sleep and Circadian Studies},

author = {I. Schöllhorn and O. Stefani and C. Blume and C. Cajochen},

url = {https://www.mdpi.com/2624-5175/5/4/44},

doi = {https://doi.org/10.3390/clockssleep5040044},

year  = {2023},

date = {2023-11-01},

urldate = {2023-11-01},

journal = {Clocks & Sleep},

abstract = {Abstract

It is well known that variations in light exposure during the day affect light sensitivity in the evening. More daylight reduces sensitivity, and less daylight increases it. On average days, we spend less time outdoors in winter and receive far less light than in summer. Therefore, it could be relevant when collecting research data on the non-image forming (NIF) effects of light on circadian rhythms and sleep. In fact, studies conducted only in winter may result in more pronounced NIF effects than in summer. Here, we systematically collected information on the extent to which studies on the NIF effects of evening light include information on season and/or light history. We found that more studies were conducted in winter than in summer and that reporting when a study was conducted or measuring individual light history is not currently a standard in sleep and circadian research. In addition, we sought to evaluate seasonal variations in a previously published dataset of 72 participants investigating circadian and sleep effects of evening light exposure in a laboratory protocol where daytime light history was not controlled. In this study, we selectively modulated melanopic irradiance at four different light levels (<90 lx). Here, we aimed to retrospectively evaluate seasonal variations in the responsiveness of the melanopsin system by combining all data sets in an exploratory manner. Our analyses suggest that light sensitivity is indeed reduced in summer compared to winter. Thus, to increase the reproducibility of NIF effects on sleep and circadian measures, we recommend an assessment of the light history and encourage standardization of reporting guidelines on the seasonal distribution of measurements.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Blume, C.; Niedernhuber, M.; Spitschan, M.; Slawik, H. C.; Meyer, M. P.; Bekinschtein, T. A.; Cajochen, C.

Melatonin suppression does not automatically alter sleepiness, vigilance, sensory processing, or sleep Journal Article

In: SLEEP, 2022.

@article{Blume2022,

title = {Melatonin suppression does not automatically alter sleepiness, vigilance, sensory processing, or sleep},

author = {C. Blume and M. Niedernhuber and M. Spitschan and H. C. Slawik and M. P. Meyer and T. A. Bekinschtein and C. Cajochen},

doi = {https://doi.org/10.1093/sleep/zsac199},

year  = {2022},

date = {2022-08-23},

journal = {SLEEP},

abstract = {Pre-sleep exposure to short-wavelength light suppresses melatonin and decreases sleepiness with activating effects extending to sleep. This has mainly been attributed to melanopic effects, but mechanistic insights are missing. Thus, we investigated whether two light conditions only differing in the melanopic effects (123 vs. 59 lux melanopic EDI) differentially affect sleep besides melatonin. Additionally, we studied whether the light differentially modulates sensory processing during wakefulness and sleep.

Twenty-nine healthy volunteers (18-30 years, 15 women) were exposed to two metameric light conditions (high- vs. low-melanopic, ≈60 photopic lux) for 1 hour ending 50 min prior to habitual bed time. This was followed by an 8-h sleep opportunity with polysomnography. Objective sleep measurements were complemented by self-report. Salivary melatonin, subjective sleepiness, and behavioural vigilance were sampled at regular intervals. Sensory processing was evaluated during light exposure and sleep on the basis of neural responses related to violations of expectations in an oddball paradigm.

We observed suppression of melatonin by ≈14 % in the high- compared to the low-melanopic condition. However, conditions did not differentially affect sleep, sleep quality, sleepiness, or vigilance. A neural mismatch response was evident during all sleep stages, but not differentially modulated by light. Suppression of melatonin by light targeting the melanopic system does not automatically translate to acutely altered levels of vigilance or sleepiness or to changes in sleep, sleep quality, or basic sensory processing. Given contradicting earlier findings and the retinal anatomy, this may suggest that an interaction between melanopsin and cone-rod signals needs to be considered.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Wislowska, M.; Klimesch, W.; Jensen, O.; Blume, C.; Schabus, M.

Sleep-specific processing of auditory stimuli is reflected by alpha and sigma oscillations Journal Article

In: Journal of Neuroscience, 2022.

Angerer, M.; Schabus, M.; Pichler, G.; Angerer, B.; Scarpatetti, M.; Blume, C.

From Dawn to Dusk – Mimicking Natural Daylight Exposure Improves Circadian Rhythm Entrainment in Patients with Severe Brain Injury Journal Article

In: SLEEP, 2022.

Angerer, M.; Wilhelm, F. H.; Liedlgruber, M.; Pichler, G.; Angerer, B.; Scarpatetti, M.; Blume, C.; Schabus, M.

Does the Heart Fall Asleep? - Diurnal Variations of Heart Rate Variability in Patients with Disorders of Consciousness. Journal Article

In: Brain Sciences, 2022.

Ameen, M. S.; Heib, D. P. J.; Blume, C.; Schabus, M.

The brain selectively tunes to unfamiliar voices during sleep Journal Article

In: Journal of Neuroscience, 2022.

Blume, C.; Schoch, S. F.; Vienneau, D.; Röösli, M.; Kohler, M.; Moeller, A.; Kurth, S.; Usemann, J.

Association of transportation noise with sleep during the first year of life: a longitudinal study Journal Article

In: Environmental Research, 2021.

Bahr, A.; Blume, C.; Eichhorn, K.; Kubon, S.

With #IchBinHanna, German academia protests against a law that forces researchers out Journal Article

In: Nature Human Behaviour, 2021.

Wielek, T.; Blume, C.; Wislowska, M.; del Giudice, R.; Schabus, M.

Decoding brain responses to names and voices across different vigilance states Journal Article

In: Sensors, 2021.

Blume, C.; Cajochen, C.

‘SleepCycles’ package for R - A free software tool for the detection of sleep cycles from sleep staging Journal Article

In: MethodsX, 2021.

Spitschan, M.; Schmidt, Marlene H.; Blume, C.

Transparency and open science principles in reporting guidelines in sleep research and chronobiology journals Journal Article

In: Wellcome Open Research, 2020.

@article{Spitschan2020,

title = {Transparency and open science principles in reporting guidelines in sleep research and chronobiology journals},

author = {M. Spitschan and Marlene H. Schmidt and C. Blume},

doi = {https://doi.org/10.12688/wellcomeopenres.16111.1},

year  = {2020},

date = {2020-07-20},

journal = {Wellcome Open Research},

abstract = {Background: "Open science" is an umbrella term describing various aspects of transparent and open science practices. The adoption of practices at different levels of the scientific process (e.g., individual researchers, laboratories, institutions) has been rapidly changing the scientific research landscape in the past years, but their uptake differs from discipline to discipline. Here, we asked to what extent journals in the field of sleep research and chronobiology encourage or even require following transparent and open science principles in their author guidelines.

Methods: We scored the author guidelines of a comprehensive set of 28 sleep and chronobiology journals, including the major outlets in the field, using the standardised Transparency and Openness (TOP) Factor. This instrument rates the extent to which journals encourage or require following various aspects of open science, including data citation, data transparency, analysis code transparency, materials transparency, design and analysis guidelines, study pre-registration, analysis plan pre-registration, replication, registered reports, and the use of open science badges.

Results: Across the 28 journals, we find low values on the TOP Factor (median [25th, 75th percentile] 2.5 [1, 3], min. 0, max. 9, out of a total possible score of 28) in sleep research and chronobiology journals.

Conclusions: Our findings suggest an opportunity for sleep research and chronobiology journals to further support the recent developments in transparent and open science by implementing transparency and openness principles in their guidelines and making adherence to them mandatory.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Blume, C.; Schmidt, Marlene H.

When the girdle of social timing relaxes: Effects of the COVID-19 lockdown on human sleep Journal Article

In: The Science Breaker, 2020.

Blume, C.; Schmidt, Marlene H.; Cajochen, C.

Effects of the COVID-19 lockdown on human sleep and rest-activity rhythms Journal Article

In: Current Biology, 2020.

@article{Blume2020b,

title = {Effects of the COVID-19 lockdown on human sleep and rest-activity rhythms},

author = {C. Blume and Marlene H. Schmidt and C. Cajochen},

url = {http://www.chronobiology.ch/wp-content/uploads/2021/09/1-s2.0-S096098222030837X-main.pdf},

doi = {https://doi.org/10.1016/j.cub.2020.06.021},

year  = {2020},

date = {2020-06-10},

journal = {Current Biology},

abstract = {In modern societies, human rest-activity rhythms and sleep result from the tensions and dynamics between the conflicting poles of external social time (e.g., work hours and leisure activities) and an individual’s internal biological time. A mismatch between the two has been suggested to induce ‘social jetlag’ [SJL; 1] and ‘social sleep restriction’ (SSR), that is, shifts in sleep timing and differences in sleep duration between work days and free days. Social jetlag [2, 3] and sleep restrictions [4] have repeatedly been associated with negative consequences on health, mental wellbeing, and performance. In a large-scale quasi-experimental design, we investigated the effects of the phase with the strictest COVID-19 restrictions on the relationship between social and biological rhythms as well as sleep during a six-week period (mid-March until end of April 2020) in three European societies (Austria, Germany, Switzerland). We found that, on one hand, the restrictions reduced the mismatch between external (social) and internal (biological) sleep-wake timing, as indexed by significant reductions in SJL and SSR, with a concomitant increase in sleep duration. Sleep quality on the other hand was slightly reduced. The improved individual sleep-wake timing can presumably be attributed to an increased flexibility of social schedules, for instance due to more work being accomplished from home. However, this unprecedented situation also led to a significant increase in self-perceived burden, which was attendant to the decrease in sleep quality. These adverse effects may be alleviated by exposure to natural daylight as well as physical exercising.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Angerer, M.; Schabus, M.; Raml, M.; Pichler, G.; Kunz, A. B.; Scarpatetti, M.; Trinka, E.; Blume, C.

Actigraphy in brain-injured patients – A valid measurement for assessing circadian rhythms? Journal Article

In: BMC Medicine, 2020.