Emerging research highlights the significant effects of shift work on health, particularly sleep. Sleep is essential for the brain and body, facilitating memory consolidation, emotional processing, and physical repair. According to Professor Russell Foster, a sleep scientist at Oxford University, "Sleep is a pillar of our health" alongside diet and exercise, emphasizing the need to manage it effectively.
Read More
The consequences of shift work extend beyond fatigue, potentially disrupting vital biological processes. One major finding is that the brain clears itself during sleep through a system known as the glymphatic system, which removes waste accumulated while awake. Professor Hugh Markus, a neurologist at the University of Cambridge, has researched this process, discovering that individuals with impaired drainage systems—evidenced through brain scans—are more likely to develop dementia later in life. He noted that disrupted drainage could play a critical role in dementia prediction among healthy populations.
Research conducted by the Karolinska Institute in Sweden examined over 13,000 shift workers and associated mid-life shift work with a 36% increased risk of dementia, a risk that intensified the longer the individual worked shifts. While Foster cautions against directly linking poor sleep to dementia, he suggests it could be a risk factor for vulnerable individuals. Markus adds that other health factors, such as blood pressure and diabetes, also contribute significantly to dementia risk.
In addition to cognitive concerns, there are indications that sleep disruption could elevate heart disease risk. An analysis of 35 studies found that reduced sleep to around 4.5 hours for multiple nights heightened immune system activity, which, while beneficial for fighting infections, can lead to inflammation associated with heart disease. Sleep disruptions also increase cortisol levels, further complicating health outcomes by promoting insulin resistance, which can lead to diabetes.
Moreover, the World Health Organization's International Agency for Research on Cancer has classified night shift work as "probably carcinogenic to humans," citing potential links to breast, prostate, and colorectal cancers. This classification may stem from disrupted circadian rhythms that affect melatonin production and contribute to chronic inflammation.
The debate around sleep patterns has also garnered attention. Historian Roger Ekirch suggests that insomnia reflects a historical pattern of sleep rather than a modern disorder, proposing a possible re-emergence of biphasic sleep—sleeping in two intervals. Some research indicates that napping can reduce sleepiness and improve alertness among shift workers.
Anna Moen is investigating the prevalence and health implications of biphasic sleep among shift workers. Her findings thus far reveal that existing studies offer inconsistent definitions and results regarding this sleep pattern. Moen aims to rigorously assess how common biphasic sleep is and whether it could provide health benefits.
Through her studies, Moen seeks to help shift workers, like her husband, who struggle with sleep patterns influenced by their work schedules. She advocates for recognizing and adapting to the body's natural signals rather than resisting them, hoping to provide evidence-based guidance for better sleep choices among shift workers.