Sunlight is a crucial factor in regulating the circadian rhythm, the mechanism that controls the natural sleep-wake cycle, says Dr. Nguyen Huu Khanh from the Neuroscience Center at Tam Anh General Hospital in Ho Chi Minh City. Natural light directly affects the hypothalamus, the part of the brain that controls melatonin production, the hormone primarily responsible for promoting sleepiness.

Exposure to light at appropriate times of the day, especially in the late afternoon, helps the body adjust and prepare for nighttime sleep, stabilizing the circadian rhythm. This makes it easier to fall asleep at night and wake up refreshed in the morning.

In addition to regulating the body clock, sunlight also stimulates the body's production of vitamin D, an essential nutrient for the immune system, nervous system, and sleep. According to Dr. Khanh, vitamin D deficiency increases the risk of insomnia and poor sleep quality, leading to persistent daytime fatigue. Afternoon sunlight helps the body absorb vitamin D naturally through the skin.

Those who stay indoors or work in closed offices all day may experience a disrupted circadian rhythm, which can lead to poor sleep, early awakening, or prolonged fatigue. Spending 15-30 minutes each afternoon outdoors, engaging in light exercise under the sun, helps relax the body, relieve stress after work, breathe in fresh air, and improves sleep.

Jogging in the afternoon promotes relaxation and increases vitamin D synthesis. Photo: Thanh Nhan

Jogging in the afternoon promotes relaxation and increases vitamin D synthesis. Photo: Thanh Nhan

For better sleep quality, doctors recommend exposure to natural light and a healthy lifestyle, limiting electronic device use before bedtime, avoiding late dinners, refraining from coffee or alcohol in the evening, and maintaining a consistent sleep-wake schedule. A balanced diet rich in fruits and vegetables, while limiting processed foods and sugary drinks, is also advised. Supplementing with natural nutrients like blueberry and ginkgo biloba, known for their antioxidant properties and support for brain function and sleep improvement, can also be beneficial.

Individuals experiencing sleep disorders such as difficulty falling asleep, restless sleep, frequent nighttime awakenings, sleepwalking, or prolonged insomnia should consult a neurologist. In some cases, doctors may recommend a polysomnography (PSG) to record brain waves, heart rate, breathing patterns, and eye movements during sleep. This helps assess sleep quality, detect potential disorders such as sleep apnea, restless legs syndrome, sleepwalking, narcolepsy, and determine appropriate treatment. Depending on the cause, doctors may recommend cognitive behavioral therapy, natural sleep improvement techniques, or short-term medication.

Phuong Pham