Circadian Phase, Sleepiness, and Light Exposure Assessment in Night Workers With and Without Shift Work Disorder

Shift work and long work hours, such as 12-hour shifts, can disturb sleep and circadian rhythms. Shift work disorder is a circadian rhythm disorder in which excessive sleepiness and/or insomnia due to work schedule occur. There is a circadian misalignment between the timing of the sleep/wake schedule and the circadian pressures for sleep and wakefulness. Between 10% and 38% of nightshift and rotating shift workers experience shift work disorder. There can be interruptions during sleep caused by light, noise, and social obligations when sleep occurs at unusual times, resulting in a short sleep duration/inadequate sleep and poor sleep quality. Sleep logs provide valuable information. To improve the quantity and quality of sleep, the sleep environment and timing of light exposure need to be optimized, and limiting interruptions during sleep is recommended. Wake-promoting agents such as armodafinil prior to work may be needed for fatigue management. Validated tools can aid in diagnosis, and there may be an underutilization of sleep specialists in these patients.

Get full-text (via PubEx)

Nighttime Blue Light Exposure and Breast Cancer

Osteopathic Family Physician ◽

10.33181/13013 ◽

2021 ◽

pp. 30-33

Author(s):

David Jaynes ◽

Paul Switzer

Keyword(s):

Breast Cancer ◽

Risk Factor ◽

Blue Light ◽

Shift Work ◽

Light Exposure ◽

Night Shift ◽

Background Information ◽

Common Disease ◽

Essential Information ◽

Night Shift Work

The purpose of this article is to provide background information and the current understanding of a less familiar cause of female breast cancer; exposure to ultraviolet light at night. Breast cancer is a common disease that causes significant morbidity and mortality in women. There are several risk factors for breast cancer, most of which are genetic and environmental in nature. An often-overlooked risk factor is exposure to blue light during night shift work, which decreases melatonin production. One of the many cancer-preventing properties of melatonin is to limit estrogen production. Increased lifetime exposure to estrogen is a well-known cause of breast cancer. Awareness of nighttime blue light exposure as a breast cancer risk factor by women doing night shift work and those exposed to nighttime light via smartphones and laptops, is essential information to know so that protective measures can be taken.

Get full-text (via PubEx)

Changes in work schedule affect the prevalence of shift work disorder among Norwegian nurses – a two year follow-up study

Chronobiology International ◽

10.1080/07420528.2021.1896535 ◽

2021 ◽

pp. 1-9

Author(s):

Siri Waage ◽

Ståle Pallesen ◽

Bente Elisabeth Moen ◽

Øystein Vedaa ◽

Eirunn Thun ◽

...

Keyword(s):

Shift Work ◽

Work Schedule ◽

Follow Up Study ◽

Shift Work Disorder

Get full-text (via PubEx)

P014 Shift work disorder and the prevalence of help seeking behaviours for sleep concerns in Australia

SLEEP Advances ◽

10.1093/sleepadvances/zpab014.062 ◽

2021 ◽

Vol 2 (Supplement_1) ◽

pp. A26-A26

Author(s):

B Brown ◽

M Crowther ◽

S Appleton ◽

Y Melaku ◽

R Adams ◽

...

Keyword(s):

Shift Work ◽

Help Seeking ◽

Management Strategy ◽

Sleep Problems ◽

Caffeine Consumption ◽

Shift Workers ◽

Standard Work ◽

Shift Work Disorder ◽

Help Seeking Behaviour ◽

Seeking Help

Abstract Introduction Shift work disorder is a circadian rhythm sleep-wake disorder, defined by symptoms of insomnia and excessive levels of sleepiness resulting from work that occurs during non-standard hours. Sleep problems are common in shift workers, yet our understanding of help-seeking behaviours for sleep in shift workers is limited. Methods As a part of a national sleep health survey, data were collected on the help-seeking behaviours for sleep problems in an online sample of Australian individuals on non-standard work schedules (n=448). Of the sample of non-standard workers, 10.5% (n=41) met the criteria for probable shift work disorder (pSWD). Results Non-standard workers with pSWD did not seek help for sleep problems at higher rates than workers without SWD (p = .979). General practitioners were the most reported healthcare professional sought out for sleep problems of individuals with pSWD. Self-management was common in workers with pSWD, with a high self-reported prevalence of alcohol use (31.7%) as a sleep management strategy, and caffeine consumption (76.9%) as a sleepiness management strategy. The majority of individuals with pSWD reported the mentality of ‘accept it and keep going’ as a sleepiness management strategy, highlighting a potential barrier to help-seeking behaviour in workers with pSWD. Discussion These findings provide novel insight into the help-seeking behaviours of individuals with pSWD. There is a need for further research to understand why individuals at risk for shift work disorder are not actively seeking help, and to develop health promotion and intervention strategies to improve engagement with healthcare professionals.

Get full-text (via PubEx)

Rest-activity cycles and melatonin phase angle of circadian entrainment in people without cone-mediated vision

10.1101/2020.06.02.129502 ◽

2020 ◽

Author(s):

Manuel Spitschan ◽

Corrado Garbazza ◽

Susanne Kohl ◽

Christian Cajochen

Keyword(s):

Ganglion Cells ◽

Light Exposure ◽

Activity Patterns ◽

External World ◽

Circadian Phase ◽

Cone System ◽

Retinohypothalamic Tract ◽

Activity Cycles ◽

Phase Angles ◽

Rest Activity

AbstractLight is strong zeitgeber to the human circadian system, entraining internal rhythms in physiology and behaviour to the external world. This is mediated by the melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs), which sense light in addition to the classical photoreceptors, the cones and rods. Circadian responses depend on light intensity, with exposure to brighter light leading to bigger circadian phase shifts and melatonin suppression. In congenital achromatopsia (prevalence 1 in 30,000 to 50,000 people), the cone system is non-functional, resulting in light avoidance and photophobia at light levels which are tolerable and habitual to individuals with a normal, trichromatic retina. Here, we examined chronotype and self-reported sleep, actigraphy-derived rest-activity cycles and increases melatonin in the evening in a group of genetically confirmed congenital achromats. We found normal rest-activity patterns in all participants, and normal melatonin phase angles of entrainment in 2/3 of our participants. Our results suggest that a functional cone system and exposure to daytime light intensities are not necessary for regular behavioural and hormonal entrainment. This may point to a compensation mechanism in circadian photoreception, which in conjunction with non-photic zeitgebers, ensures synchronisation of activity to the external world.Significance statementRhythms in physiology and behaviour are synchronised to the external cycle of light exposure. This is mediated by the retinohypothalamic tract, which connects the photoreceptors in the eye with the “circadian pacemaker” in our brain, the suprachiasmatic nucleus. What happens to our circadian rhythm when we lack the cone photoreceptors in the eye that enable us to see in daylight? We examined this question in a group of rare congenital achromats. Our work reveals that normal rhythms in rest and activity, and production of hormones, does not require a functional cone system.

Get full-text (via PubEx)