The results of our study on the effects of near-infrared light (NIR) on health and well-being in people suffering from sleep loss is published today. In a double-blind, randomized, placebo-controlled study, the effects of three NIR light (850 nm) doses (1, 4, or 6.5 J·cm−2) were examined against the placebo. Exposure was presented five days…
The time of day that an Olympic swimming race takes place may affect athletes’ performance and could mean the difference between gold, silver and bronze, according to a study published in Scientific Reports. Countries selected to host the Olympics may adjust race times to accommodate broadcast across continents, requiring athletes to compete at different, sometimes…
Marijke Gordijn from Chrono@Work co-authors a paper, published in Scientific Reports, about how the eye uses natural light information to synchronize the biological clock to the outdoor light, even when clouds are covering the sky. The mammalian circadian system encodes both absolute levels of light intensity and color to phaselock (entrain) its rhythm to the…
Marijke Gordijn is a co-author of a study featured at Sleep. Study objectives To determine the effect of light exposure on subsequent sleep characteristics under ambulatory field conditions. Methods Twenty healthy participants were fitted with ambulatory PSG and wrist-actigraphs to assess light exposure, rest-activity, sleep quality, timing and architecture. Laboratory salivary dim-light melatonin onset (DLMO)…
Marijke Gordijn is co-author of a study investigating the relationship between vegetarianism and winter depression, together with researchers from Finland and the university medical center in Groningen. A Background and Aim: Seasonal patterns of food intake are found in healthy individuals and particularly in patients with seasonal affective disorder (SAD). One nutritional choice is a…
To examine whether acute changes in cognitive empathy might mediate the impact of light therapy on mood, we assessed the effects of a single light-therapy session on mood and cognitive empathy in 48 premenstrual women, including 17 who met Premenstrual Symptoms Screening Tool criteria for moderate-to-severe premenstrual syndrome / premenstrual dysphoric disorder (PMS/PMDD). Using a…
Marijke Gordijn is co-author of a study that investigates how ambulatory measurements can help in estimating the phase and period of the human circadian clock. Light is the most potent time cue that synchronizes (entrains) the circadian pacemaker to the 24-h solar cycle. This entrainment process is an interplay between an individual’s daily light perception…
Marijke Gordijn is coauthor of a study investigating sleep disturbances in PKU. Sleep problems have not been directly reported in phenylketonuria (PKU). In PKU, the metabolic pathway of phenylalanine is disrupted, which, among others, causes deficits in the neurotransmitters and sleep modulators dopamine, norepinephrine, and serotonin. Understanding sleep problems in PKU patients may help explain…
What is sleep? Sleep as part of our daily life, This chapter describes the basic principles of sleep and wake regulation, the effects of sleep deprivation due to a mismatch between sleep and the biological clock, and what you can do about it. Every evening, a large behavioral change occurs in almost all people. In…
The Award recognizes the paper published in Ergonomics during the preceding year that best contributes to the advancement of ergonomics. You can find our paper, listed for the Liberty Mutual award, entitled Sleep and need for recovery in shift workers: do chronotype and age matter? at http://dx.doi.org/10.1080/00140139.2015.1058426
Chronotherapeutic interventions Marijke Gordijn of Chrono@Work co-authored a Dutch paper on Chronotherapeutic interventions in Psychiatry. She wrote this paper together with 3 colleagues with whom she also started Chronotherapy Network Netherlands (www.cnn.nl). The paper was published in the continuing education journal Psyfar. Since 2006, Psyfar focusses on educating and testing psychiatrists, hospital pharmacists, geriatrics specialists,…
Seasonal affective disorder, winter type: current insights and treatment options Marijke Gordijn from Chrono@Work co-authored a review paper on Seasonal Affective disorders. Seasonal affective disorder (SAD), winter type, is a seasonal pattern of recurrent major depressive episodes most commonly occurring in autumn or winter and remitting in spring/summer. The syndrome has been well-known for more…
Chrono@Work’s employee Marina Giménez is the first author of a paper describing a study on the effects of a new dynamic room lighting system on sleep of patients admitted to a cardiology ward. Irregular 24 h light/dark cycles with night-time light exposure and a low amplitude are disruptive for sleep, mood and circadian rhythms. Nevertheless,…
LIght therapy to shift the biological clock has been shown to be effective, but in most cases studies are carried out in well controlled laboratory studies and with long duration light pulses. In practice, light therapy should consist of an easy to apply lighting regime to which people at home will adhere and with clear…
The therapy of first choice for treating Seasonal Affective Disorder, winter type, is light treatment. Meta analyses have shown that light therapy in the morning has the highest chance to be successful. In the Netherlands, common practice is 30-45 minutes of bright light therapy in the morning for five consecutive days. If given early in…
Light pulses of 30 min. in the morning on three consecutive days, in a home setting, in combination with dim light during the evenings, can be part of an efficient phase advancing chronotherapy protocol to shift the biological clock. It is well known from controlled laboratory experiments, that light in the morninge induces phase shifts of the biological…
Light of short wavelengths has been shown to play a key role in non-image forming responses. Due to aging, the ocular lens becomes more yellow reducing the transmission of short wavelengths in the elderly. In the present study, we make use of cataract surgery to investigate the effects of a relative increase of short wavelength transmission on melatonin-…
As the 24-hour economy continues to leave its mark on societal life, the effects of the disruption of the natural biological rhythm become more apparent. Aside from the effects this has on sleep we will also discuss the health effects in the long term. As well as potential measures to reduce the negative effects of…
A new photometric measure of light intensity that takes into account the relatively large contribution of the ipRGCs to the non-image forming (NIF) system was recently proposed. We set out to revise publications reporting on alertness scores as measured by the Karolinska Sleepiness Scale (KSS) under different light conditions in order to assess the extendibility…
This study examined associations of chronotype and age with shift-specific assessments of main sleep duration, sleep quality and need for recovery in a cross-sectional study among N ¼ 261 industrial shift workers (96.6% male). Logistic regression analyses were used, adjusted for gender, lifestyle, health, nap behaviour, season of assessment and shift schedule. Shift workers with latest versus earliest…
Various lines of evidence suggest a mechanistic role for altered cAMP-CREB (cAMP response element – binding protein) signaling in depressive and affective disorders. However, the establishment and validation of human inter-individual differences in this and other major signaling pathways has proven difficult. Here, we describe a novel lentiviral methodology to investigate signaling variation over long periods of…
Background: Seasonal affective disorder (SAD) is characterized by recurrent episodes of major depression with a seasonal pattern, treated with light therapy (LT). Duration of light therapy differs. This study investigates retrospectively whether a single week of LT is as effective as two weeks, whether males and females respond differently, and whether there is an effect of expectations as…
Light is an important environmental stimulus for the entrainment of the circadian clock and for increasing alertness. The intrinsically photosensitive ganglion cells in the retina play an important role in transferring this light information to the circadian system and they are elicited in particular by short-wavelength light. Exposure to short wavelengths is reduced, for instance, in elderly…
Human cortisol levels follow a clear circadian rhythm. We investigated the contribution of alternation of sleep and wakefulness and the circadian clock, using forced desynchrony. Cortisol levels were best described by a multiplication of a circadian and a wake-time component. The human cortisol response is modulated by circadian phase. Exposure to stress at an unnatural phase, as in…
