Most people know that sunlight is important for their health. We hear about getting outside, enjoying fresh air and spending time in nature. But did you know that the time of day you get sunlight may matter just as much as getting outside in the first place?
Morning sunlight and evening sunlight provide different signals to your brain. These signals help regulate your internal body clock, influencing when you feel awake, when you become tired and how your body prepares for sleep.
This relationship between light and the body's natural rhythms is an important topic in Andrew Huberman's book, Protocols: An Operating Manual for the Human Body. His discussion of light exposure highlights how simple daily habits can help support our natural sleep-wake cycle.
Understanding this connection may be particularly useful as we get older, when sleep patterns and daily routines can begin to change.
Why Your Body Has an Internal Clock
Your body operates on a roughly 24-hour cycle known as the circadian rhythm. This internal timing system helps coordinate important processes, including sleep, alertness, hormone release and body temperature.
One of the strongest signals that helps keep this system on schedule is light.
Specialized cells in the retina, the light-sensitive tissue at the back of your eye, detect changes in the surrounding light environment. They communicate this information to a part of the brain responsible for regulating the body's internal clock.
In simple terms, light helps your brain understand whether it is time to be awake or prepare for rest.
This is why your daily exposure to natural and artificial light can influence how you feel throughout the day.
1. Morning Sunlight Helps Signal That the Day Has Begun
Morning light is one of the most important environmental signals for regulating your sleep-wake cycle.
When your eyes receive natural daylight after waking, your brain receives information that helps establish the timing of your day. Morning light can help support alertness and keep your internal clock aligned with the natural day-night cycle.
In Protocols, Huberman emphasizes getting bright natural light early in the day, ideally outdoors. Outdoor light is generally much brighter than typical indoor lighting, even when the weather is cloudy.
You do not need to spend hours outside. A short morning walk, sitting on a patio or enjoying breakfast outdoors can be an easy way to incorporate natural daylight into your routine.
A few practical ideas include:
Open your curtains soon after waking.
Spend some time outdoors during the first part of the morning.
Take a short walk when weather and mobility allow.
Enjoy breakfast near a bright window if getting outdoors is difficult.
Remember that looking directly at the sun is never necessary. You can receive natural daylight without staring at it.
2. Why Evening Sunlight Sends a Different Signal
Here is where things get interesting.
Although morning light helps signal the beginning of the day, light exposure in the evening can influence your internal clock differently.
Bright light in the evening, particularly close to bedtime, can delay the body's natural sleep timing. It may make you feel alert later and make it harder to fall asleep at your usual time.
However, natural light around sunset is also discussed in Huberman's protocols. This exposure provides another environmental signal as the day transitions toward darkness.
The important distinction is between natural daylight during the late afternoon and evening, and prolonged exposure to bright artificial lighting later at night.
As the sun sets, gradually reducing the brightness of your surroundings can help reinforce the natural transition from daytime to nighttime.
3. Why the Difference Matters for Sleep
Have you ever spent the evening watching television in a brightly lit room, only to find that you are not particularly tired when it is time for bed?
Light exposure may be one contributing factor.
Your brain uses environmental light to help coordinate the timing of sleep-related processes, including the release of melatonin, a hormone involved in regulating sleep.
Bright light at night can suppress melatonin and interfere with the body's natural preparation for sleep.
This does not mean that one evening watching television will ruin your sleep. However, regularly spending late evenings in brightly lit environments may make it harder for some people to maintain a consistent sleep schedule.
A simple approach is to make your home brighter during the day and gradually dimmer as bedtime approaches.
4. Why This Becomes Especially Important as We Age
Sleep patterns often change as people get older.
Some older adults begin waking earlier, feeling tired during the day or experiencing more interruptions throughout the night. Changes in the circadian system, medications, health conditions and daily routines can all contribute.
Spending more time indoors may also mean receiving less natural daylight throughout the day.
For residents of retirement communities and long-term care homes, opportunities to spend time outdoors may depend on mobility, weather, staffing and daily schedules.
Even small changes can help create a more consistent routine. Sitting near a bright window during breakfast, enjoying a courtyard in the afternoon or taking a short walk with a family member can provide opportunities to experience natural daylight.
These habits are not a treatment for sleep disorders, but they can be a useful part of a healthy daily routine.
5. A Simple Light Routine to Try
You do not need complicated equipment or an expensive wellness routine to become more mindful of light exposure.
Morning
Open the curtains and allow natural daylight into your home.
Spend time outside when possible.
Try a short morning walk.
Afternoon
Spend time in naturally lit rooms.
Take opportunities to enjoy outdoor spaces.
Incorporate gentle movement into your day.
Evening
Enjoy the natural transition toward sunset when possible.
Reduce bright household lighting as bedtime approaches.
Limit screen brightness and stimulating activities before bed.
Keep your bedroom dark and comfortable.
Consistency is more important than following a perfect schedule. Your routine should also reflect your health, mobility and individual sleep needs.
Your Eyes Do More Than Help You See
It is fascinating to think that the eyes play such an important role in regulating the body's internal clock.
They do not simply allow us to read, recognize faces and navigate our surroundings. Specialized cells in the retina also help communicate information about the surrounding light environment to the brain.
This is another reason why looking after your eye health matters throughout life.
Conditions such as cataracts, glaucoma and age-related macular degeneration can affect vision and make everyday activities more challenging. Regular comprehensive eye examinations help monitor changes and identify potential concerns.
At Viewpoint Vision Care, we bring comprehensive eye examinations directly to retirement communities and long-term care homes, making it easier for residents to access important eye care. When new glasses are needed, residents can select and fit frames during the visit, with finished glasses delivered directly to their bedside.
Make Light Part of Your Daily Routine
The relationship between sunlight and sleep is a reminder that our health is influenced by everyday habits.
Getting natural light in the morning, enjoying daylight throughout the day and reducing bright artificial lighting in the evening are simple ways to become more mindful of your body's natural rhythms.
You do not need to change everything at once. Start with something as simple as opening the curtains in the morning or taking a few minutes to enjoy the outdoors.
Sometimes, a healthier daily routine begins with something as simple as stepping outside.