How to Optimise Light Exposure for Improving Sleep and Recovery

Light plays a more important role in our health than is often given credit for. It’s one of the most important things for regulating our circadian rhythm—the internal clock governing nearly all biological processes, including our sleep-wake cycles, hormone release, and alertness levels. This connection between light and our bodily functions means that managing light exposure should not be taken lightly, especially if you frequently work irregular or night shifts.

One of the foundational pieces we’ve talked about throughout the SFR120 Programme is the importance of circadian rhythm regulation, as it’s essential for optimal sleep, recovery, and fatigue prevention. However, long shifts, night shifts, seeing no natural light, or being on your digital devices late at night can trigger the complete opposite of a good circadian rhythm. These factors can significantly disrupt your body's natural timing, leading to issues such as sleep disorders, impaired cognitive function, and increased stress levels.

We understand that getting natural light isn’t always an option in your line of work, however, there are still ways that you can measure and manage your light exposure to benefit you. This is where lux measurements, the unit for measuring illuminance, come into play, offering a quantitative way to harness the benefits of sunlight effectively. (More on this below, but first, a bit of science).

The science of sunlight and circadian rhythm

Circadian rhythm is the body's internal clock running in the background, regulating the sleep-wake cycle among other vital functions. This clock is primarily synchronized by exposure to natural light and darkness, signaling when it’s time to wake up and wind down. Sunlight has a profound effect on this system, influencing hormone release (think: melatonin, the sleep hormone), body temperature, and other bodily functions that help us feel alert or ready for sleep.

Since you might be awake at odd hours for shifts or called out unexpectedly, keeping this internal clock running correctly can be challenging. Disruptions in the circadian rhythm can lead to poor sleep quality, increased fatigue, and even long-term health issues. Studies have found a link between circadian rhythm disruption and decreased performance along with an increased risk of metabolic dysfunction and weight gain.

The role of lux measurements

Lux gauges the intensity of light that hits a surface. It’s a useful factor in assessing adequate exposure to natural light. For instance, a bright office has about 400 lux of illumination, while a cloudy day might provide over 1,000 lux. In contrast, indoor lighting typically offers a meager 100 lux or less — insufficient for circadian rhythm regulation.

Knowing the lux values of different environments can help you plan your exposure to light. For optimal circadian rhythm management, it's recommended to aim for exposure to natural light environments of at least 500 to 1,000 lux for about 30 minutes each day. This can be particularly effective in the morning to help signal the body that it’s time to start the day, enhancing alertness and setting a healthy sleep pattern.

Practical applications

Morning light exposure: Start the day with exposure to bright sunlight. If possible, take morning breaks outdoors or near windows to boost your natural light intake. This helps reset the circadian clock, promoting wakefulness throughout the shift and better sleep at night.

Utilize lux measurement tools: Small, portable lux meters or smartphone apps can be used to measure light levels in various settings to help you track whether you are getting enough light exposure during the day.

Manage indoor lighting: When natural light isn’t an option, particularly during night shifts or in windowless environments, adjustable artificial lighting can help. Lights that mimic natural light patterns, ideally those that can provide over 500 lux, may help to enhance alertness when needed.

Evening wind-down: Conversely, reducing exposure to bright light, especially blue light from screens, before bedtime can help signal the body that it’s time to sleep, aiding in faster sleep onset and deeper sleep cycles. Research has found that blue light exposure after sunset offsets the body’s melatonin release, which will make it harder to fall asleep.

Use blue-light-blocking glasses: While the research behind these glasses is inconsistent, it’s worth testing how your body and mind react to wearing them. Wearing ones with orange or red lenses in the evening may limit the impact of blue light from screens and help promote relaxation and readiness for sleep, potentially aiding in the natural increase of melatonin production. If you’re tracking your sleep, this is a great opportunity to see how your data changes if you wear these glasses at night.

Consistent schedule: As much as possible, try to keep a regular schedule for waking up and going to bed, even on days off. This consistency is one of the best hacks you can do to help reinforce your body’s internal clock and improve long-term recovery and well-being.