The night shift is a hidden cost that affects millions of workers, from nurses and paramedics to engineers and factory workers, who keep the country running while everyone else sleeps. The toll of shift work on the body is significant, with potential consequences including heart attacks, strokes, cancer, mental illness, and memory loss. The scientific evidence is increasingly difficult to ignore, and researchers are exploring ways to mitigate the effects of disrupted sleep. One surprising theory is that splitting sleep into two separate blocks may be more effective for people working through the night.
Sleep is not just a rest for the brain and body; it is a crucial process that consolidates memories, processes emotions, solves problems, strengthens immune defenses, and repairs muscle tissue. During sleep, the brain cleans itself through the glymphatic system, which washes away waste products that accumulate during waking hours. Disruption of this system has been linked to an increased risk of dementia, with proteins like amyloid and tau accumulating in the brain. A Swedish study found that shift work in mid-life was associated with a 36% higher risk of dementia, with the risk rising the longer someone had worked shifts.
Sleep disturbance can also increase the risk of heart disease, with reduced sleep raising the stress hormone cortisol, which promotes insulin resistance and diabetes. The World Health Organization's International Agency for Research on Cancer has classified night shift work as "probably carcinogenic to humans," citing evidence for links to breast, prostate, colon, and colorectal cancers. The disruption to the body's circadian system alters the timing of melatonin production, a hormone with tumor-suppressing properties, and reduces vitamin D from lack of daylight.
Biphasic sleep, or sleeping in two distinct blocks, has been suggested as a potential solution for shift workers. A study in the Arctic Circle found that shift workers naturally slept in two blocks, from nine in the morning until one, then again in the afternoon before the next shift. This pattern echoes the pre-industrial sleep rhythm, where humans often slept in two blocks before artificial lighting. Researchers suggest that this may be a more natural rhythm, and laboratory experiments support the biological claim.
However, the dearth of evidence around biphasic sleep is a concern. Existing research is fragmented, with no agreed definition of what constitutes biphasic sleep. Dr. Line Victoria Moen is investigating the prevalence and health outcomes of biphasic sleep among shift workers, with the aim of developing clear clinical guidelines. Napping during shift work has been shown to reduce sleepiness and improve alertness, and Moen's research may provide valuable insights into the potential benefits of splitting sleep.
In conclusion, the night shift is a hidden cost that affects the body in numerous ways, with potential consequences for health and well-being. While the scientific evidence is compelling, more research is needed to fully understand the implications of disrupted sleep and to develop effective solutions for shift workers. The potential benefits of biphasic sleep and napping during shift work are promising, and further exploration of these avenues may lead to improved health outcomes for those who work through the night.
