Blue Light of Mobile Phones & Our Sleep
By Dr Brij Mohan Sharma & Dr Dipika Chamoli Shahi
After sunset, nature signals us to rest, but the glow of our mobile phone tells us—there is still a night to explore!
When Alexander ‘conquered the world’, did he walk around with his sword in his hand all the time? Certainly not. The sword was his instrument, but he remained its master. Today, we too possess a remarkable instrument—the mobile phone. But sometimes, with a touch of irony, it seems that the situation has reversed: the mobile is no longer in our hands; rather, we are in the hands of the mobile!
Today, the mobile phone has become an inseparable part of our lives. Checking the phone immediately after waking up and remaining connected to the screen until bedtime has become routine for many of us. From education, employment and business to banking, news, entertainment and social communication, mobile technology has transformed the way we live and made many aspects of life easier and more convenient.
However, when a technology designed to make our lives easier begins to take away our sleep, attention and peace of mind, it is time to pause and reflect. The real question is not merely how many hours we use our mobile phone, but when, why and whether we really need to use it. Technology should remain our servant—not quietly become the master of our lives.
Our body follows the circadian rhythm, i.e., the cycle of day and night. Each one of us has a biological clock for when to wake up and when to sleep during a cycle of 24 hours. Operating on an approximately 24-hour cycle, it regulates sleep and wakefulness along with body temperature, hormones and several other biological processes. Being awake or asleep depends on a balance of biochemicals: cortisol and orexin push the brain toward wakefulness, whereas melatonin shifts it toward sleep (Han et al., 2012). Light plays a crucial role in keeping this internal clock synchronised. Daylight signals the body to remain alert and active, while darkness prepares it for rest.
Scientific studies have associated evening exposure to light-emitting electronic screens with reduced melatonin production and delayed sleep. The light emitted by mobile phones, tablets and computers contains a significant amount of blue light which has melanopsin that is known to decrease the secretion of melatonin i.e. the sleep hormone (Blazhkova et al., 2025). Exposure to light from these devices in the evening can interfere with the natural processes that regulate the biological clock. The effect can be more significant when screens are viewed very closely, at high brightness and for prolonged periods.
However, scientifically, it would be incorrect to say that blue light alone is responsible for poor sleep. The activity we perform on the mobile phone is equally important. Scrolling through social media, watching short videos, playing online games, responding to messages or reading stimulating news can keep the brain highly active. While the body is preparing to rest, the brain continues receiving new information and emotional stimulation. We may reach the bed physically, but mentally our brain can remain “online”. We must remember that the human body is a great machine with well-defined functions at day and night and that need to be respected which is known as discipline in normal parlance.
One of the strongest attractions of smartphones is their continuously changing content and instant feedback. One notification pulls us towards the screen, followed by a message, a short video and then another. We may tell ourselves that we will use the phone for only five minutes, yet half an hour—or even longer—can pass unnoticed. Thus, mobile phones may not only reduce the amount of time available for sleep but can also interfere with the mental transition required for restful sleep.
Nowadays many of us are reporting sleep disturbances, sleep issues, insomnia and other sleep related disorders. It needs to be understood that adequate sleep is essential for a healthy body and a healthy brain. During sleep, the body undergoes important restorative processes, while the brain organises information received during the day and strengthens memory. Regularly sleeping late or maintaining an irregular sleep schedule can affect concentration, mood and daytime performance. Therefore, sleep should not be treated as “whatever time is left after everything else is done”; it should be regarded as a fundamental health requirement. Four different types of brain waves are emitted by the brain, beta when the brain is active, alpha when brain is relaxing, theta when brain is in deep sleep, and delta when in further deep sleep. In 8 hours of the sleep cycle a normal adult is in deep sleep for a maximum of 60-110 minutes (BodySpec Team, 2025). So it is very important to take our sleep as a necessary ritual.
The issue is particularly important for children and adolescents. Digital devices are now widely used not only for education but also for entertainment. Late-night mobile use can delay bedtime and reduce total sleep. It is further noted that it is not only the sleep issue but in the long run it can be transformed in some kind of psychological issues as proved by science. Adequate sleep is essential for children’s learning, attention, memory, behaviour and healthy development. Therefore, simply imposing a screen-time limit is not enough. Families need to establish a healthy routine that gives appropriate space to study, play, physical activity, conversation, relaxation and sleep.
Prolonged screen use can also contribute to digital eye strain, with symptoms such as tiredness, dryness, irritation, headache and temporary blurred vision and also associated with depression, anxiety, stress and other psychological disorders. One reason is that people tend to blink less frequently while concentrating on a screen. A simple approach is the 20-20-20 rule: approximately every 20 minutes, look at something about 20 feet away for at least 20 seconds (WebMD Editorial Team & Helmer, 2026). Maintaining a comfortable viewing distance and adequate ambient lighting can also help reduce eye strain.
One practical strategy is to develop the habit of a “Digital Sunset”. This means gradually stopping the use of mobile phones and other screens about an hour before bedtime. Instead of keeping the phone beside the pillow, place it at some distance from the bed. Turn off unnecessary notifications and reduce screen brightness during the evening. Night-mode or warmer-display settings may reduce some aspects of evening light exposure, but they should not be considered a complete solution. The most important step is to reduce prolonged and stimulating screen use before bedtime.
Morning exposure to natural light can also help synchronise the body’s biological clock with the day–night cycle. Spending some time outdoors in natural daylight, maintaining regular sleep and wake times, engaging in physical activity during the day and keeping bedroom lighting subdued at night are all valuable components of healthy sleep habits.
Mobile discipline should not be imposed only on children. If parents themselves continue using their phones in bed at night, it becomes difficult to teach children healthy digital habits. Families can therefore create a “Family Digital Sunset”. After a mutually agreed time, everyone can put their phones aside and replace screen time with conversation, reading, gentle music or another calming activity. For children, this becomes not merely a rule but a positive example set by the entire family.
We must remember that technology is not our enemy. Mobile phones have brought education, healthcare, communication and knowledge closer to us than ever before. The problem is not technology itself, but its unbalanced use. We need to create harmony between technology and our natural biological rhythms.
Just as a mobile phone needs regular charging, our body and brain also need daily restoration through adequate sleep. So let us make a simple resolution:
“Before going to sleep, put the mobile aside—and meet yourself.”
Ultimately, in this digital age, we must decide whether the mobile phone will remain a convenience that serves our lives or become a controller of our sleep. Good sleep is not a luxury; it is a scientific necessity for a healthy, productive and balanced life.
“When we allow the screen to rest at the right time, we allow our body and brain to rest completely.”
(Dr Brij Mohan Sharma is a National Awardee and ISRO Tutor. Dr Deepika Chamoli Shahi is a Psychologist, Clinical Hypnotherapist, Trauma Expert, and Perinatal Mental Health Expert.)
