Night Shifts Disrupt Our Bodies and Increase Disease Risk
Night work forces the body to act against its biological clock, with studies linking it to dementia, heart disease, and certain cancers. Dr. Amit Green, a sleep expert at Assuta, explains: "Staying awake when the body is programmed for sleep disrupts the circadian system and can increase the risk of morbidity."
Millions of people work at night, forcing themselves to sleep during hours when their biological clock signals the body to wake up. Recent studies point to a clear link between shift work and an increased risk of dementia, cardiovascular disease, metabolic disorders, and certain types of cancer.
Dr. Amit Green, a psychologist and sleep expert at Assuta, explains that light is the primary factor that sets the biological clock. "In the modern world, we are exposed to too little natural light during the day while working indoors, and conversely, we are exposed to an excess of artificial light from screens at night. Thus, the biological clock is disrupted from both directions," he says.
"The night is not dead time"
The consequences of night work depend not only on the number of sleep hours but also on the disruption of vital processes. While we sleep, the brain consolidates memories, and the body supports recovery and tissue repair. "The fact that we are not active does not mean the body is not active," Dr. Green emphasizes. During deep sleep, the glymphatic system helps clear waste accumulated in the brain, including amyloid and tau proteins.
A study using the UK Biobank database found that impairment of this waste-clearance system is linked to a higher risk of dementia. A Swedish study following 13,000 shift workers over 41 years found that shift work in midlife was associated with a 36% higher risk of dementia.
Impact on immunity and metabolism
An analysis of 35 studies found that reducing sleep to 4.5 hours a night for three nights significantly increases immune system activity, leading to chronic inflammation. This also raises cortisol levels, which promotes insulin resistance and diabetes. The International Agency for Research on Cancer (IARC) has classified night shift work as "probably carcinogenic to humans."
Can the damage be mitigated?
Researchers are exploring ways to reduce the harm for shift workers. One option is biphasic sleep: splitting sleep into two periods instead of trying to sleep continuously after a shift. Additionally, a short nap (20–50 minutes) during a shift can improve alertness and reduce the risk of drowsy driving.
"If you feel depressed, lacking vitality and energy, it is a sign that you need to re-examine your situation," advises Dr. Green. When such signs appear, it is advisable to seek professional advice to explore personalized treatment options, whether through melatonin or reconsidering the suitability of shift work.
