Light Exposure and Research
Indoor lighting and common technologies (computers, e-readers, smart phones) have changed the way we work and live. Before the invention of the lightbulb, sleep and work times were largely dictated by the rising and setting of the sun. Electricity and indoor lighting gave us more control over our sleep timing, no longer strictly waking and sleeping by daylight hours. Computers and other digital technology provide expanded access to entertainment, shopping, socializing, and work tasks dominated by lighted screens. We find ourselves in a 24/7 society, where we spend more time indoors during the day and are awake later at night. Regardless of what shift we work, we're exposed to less natural daylight and more indoor light (including blue light) than previous generations.
Industrial lighting, including the LED and fluorescent frequently found in hospitals, can simulate sunlight, tricking our SCN into thinking it's daytime. If light exposure can increase alertness and disrupt sleep, can we time it to our advantage while at work or in-between shifts? The short answer is maybe. In a laboratory study by Kervezee and colleagues, participants exposed to bright light treatment during an 8-hour simulated night shift experienced a change in their sleep, indicating some adaptation to the night shift schedule.
Harrison and collaborators conducted a small multimodal light intervention study within a hospital setting. The intervention included installing brighter lighting in the nurses' station, limited exposure to a bright light box when tired, blue light-blocking glasses to wear before sleep, and eye masks to wear during sleep. Nurses reported enhanced alertness while working, improved sleep quality, and a better overall quality of life.
Other studies have focused specifically on blocking blue light at strategic times of the day with blue light–blocking glasses. Two small studies of night shift workers wearing the glasses during the day showed increased daytime sleep duration, decreased sleep disruption, and improved circadian adaptation to night shift work (as measured by melatonin levels). This research may point us toward interventions where timing and exposure to bright light help nurses better adapt to night shift and early shift work and strategically blocking blue light helps improve sleep.
Although exposure and timing of bright light is of particular importance to night shift nurses, all nurses could benefit from awareness of the risks related to blue light exposure from smart phones, TVs, and other electronics before bedtime. This exposure can trigger the SCN to activate daytime circadian functions, increasing alertness and decreasing sleepiness. Technology companies have tried to overcome this effect by installing orange light "night mode" features on devices. Unfortunately, a recent study by Mason and colleagues, using randomly assigned control and intervention groups, didn't find significant improvement in sleep when using night mode.
Am Nurs Journal. 2022;17(3) © 2022 HealthCom Media