Having the television on while trying to fall asleep is a common habit for many people. The background noise and flickering light can seem comforting. However, researchers have found that sleeping with the TV on may negatively impact health.
Does the Light from TV Disrupt Sleep?
Light, especially from screens like TVs, computers, and phones, can disrupt the body’s natural sleep-wake cycle. This cycle is known as the circadian rhythm. It is primarily controlled by a part of the brain called the suprachiasmatic nucleus (SCN).
The SCN responds to light detected by the eyes. When the SCN senses light, it signals the brain to be alert and awake. Darkness causes the SCN to release melatonin, a hormone that makes you feel tired.
Having a light on can trick the brain into thinking it is still daytime. This suppresses the release of melatonin and shifts the circadian rhythm. As a result, it can be harder to fall asleep, sleep quality suffers, and you may wake up frequently.
Blue Light is Especially Disruptive
Not all light wavelengths impact sleep equally. Blue light, like that emitted from TV and phone screens, is especially likely to affect sleep patterns.
Research shows that exposure to blue light in the evening can:[1]
- Reduce melatonin release by up to 50%
- Delay the circadian rhythm by up to 3 hours
- Make it harder to fall asleep
This is because blue light wavelengths most strongly suppress melatonin and shift the body clock. The brighter the blue light, the more it will disrupt your natural sleepiness.
Does the Noise and Content Matter?
In addition to light, the noise and content of what you watch before bed can also make it harder to fall and stay asleep.
Noise Can Disrupt Sleep
Noise at night can disrupt the sleep cycle by causing more frequent awakenings. Even when we don’t fully wake up, noise can trigger micro-arousals and prevent us from getting truly deep, restorative sleep.
Studies show that noise levels as low as 35 decibels, about the level of a whisper, can impair sleep quality.[2] Noise above this range can:
- Increase the time it takes to fall asleep
- Decrease total sleep time
- Reduce time spent in deep sleep stages
- Increase movement during sleep
- Impair mood and cognitive function the following day
Although everyone has a different sensitivity to noise, TV audio can easily exceed 35 decibels. News, action movies, and other programs with jarring sounds may be particularly disruptive.
Exciting Content Can Also Interfere with Sleep
Aside from noise, the content you watch before bed matters. TV shows and movies can bring up stimulating or emotional themes. This psychological arousal can carry over into bedtime, making it harder to relax and fall asleep.
One study compared the effects of watching calm versus violent TV shows before bedtime. Those who watched exciting or violent content took longer to fall asleep and had poorer quality sleep.[3]
So not just the noise but also the themes of what you watch can interfere with your ability to wind down at night.
Sleeping with the TV On May Contribute to Insomnia
Difficulty falling or staying asleep, known as insomnia, affects up to 30% of adults.[4] Watching TV before bed, especially late at night, may contribute to insomnia.
In one survey, 94% of people with insomnia reported watching TV in bed in the hour before going to sleep. This compared to just 69% of people without insomnia.[5]
Other studies have had similar findings, with more TV viewing before bed linked to insomnia severity:[6]
- Each additional hour of TV watched after 8 pm increased the odds of insomnia by 38%
- Those who always slept with the TV on had more than double the risk of insomnia
Leaving the TV on all night may sustain the factors that disrupt sleep. The constant light, fluctuating volume, and intermittent content can repeatedly rouse you from deep slumber.
A Vicious Cycle Emerges
Experts think a vicious cycle often emerges between poor sleep and watching TV at night. The cycle may go like this:
- Difficulty sleeping prompts turning on the TV
- TV disrupts sleep further
- The resulting daytime fatigue leads to more TV at night
- Sleep becomes even worse, and so on
Breaking this cycle by switching off screens before bed is an important step in treating insomnia.
Health Risks of Long-Term TV Exposure at Night
Over the long term, disrupting sleep cycles by sleeping with the TV on may increase the risk of heart disease, obesity, diabetes, and early death. This is because poor sleep impairs the immune system and metabolism.
Heart Disease
There is a strong link between chronic sleep deprivation and heart disease. In one study tracking 500,000 people for 8 years, those getting less than 5 hours of sleep per night had a 45% greater risk of developing or dying from heart disease.[7]
Researchers think poor blood pressure regulation and high levels of inflammation caused by inadequate sleep drive the increased cardiovascular risks. Leaving the TV on at night, which interferes with sleep quality and quantity, may have similar effects on the heart.
Obesity
Getting insufficient sleep alters hormone levels in ways that can increase appetite and calorie intake.[8] Among people getting less than 6 hours of sleep per night, obesity rates have risen nearly 50% over the past 30 years.
With more TV viewing at night linked to poorer sleep quality, some experts suspect that sleeping with the TV on may indirectly contribute to obesity in the long run.
Diabetes
Poor sleep diminishes insulin sensitivity and impairs blood sugar control, increasing the risk of type 2 diabetes.[9] People who report sleep disruptions like having the TV on while sleeping have up to a 28% higher risk of developing diabetes.
Premature Death
Several large reviews have concluded those who regularly get too little sleep have up to a 15% greater risk of premature death. Researchers think chronic diseases caused by poor sleep drive the increased mortality risk.[10]
Improving sleep hygiene by turning off screens before bed may help mitigate these long-term health risks.
Tips for Breaking the Habit of Sleeping with TV On
If you regularly fall asleep with the TV on, try these tips for breaking the habit:
- Set a media curfew: Turn off all screens at least 1 hour before bedtime.
- Make the bedroom a TV-free zone: Don’t have a TV in the bedroom if possible.
- Read before bed: Replace TV time with reading a book.
- Listen to calming music: Try smooth jazz or classical
- Use white noise: Try a fan, sound machine, or tinnitus therapy device
- Keep the room dark: Use blackout curtains and avoid night lights.
- Practice good sleep habits: Stick to a consistent sleep schedule, limit caffeine, and make sure your mattress and pillows are comfortable.
Considering getting a new mattress or bedding designed for deeper sleep may also help limit awakenings.
Conclusion
Having the TV on while trying to sleep is extremely common. However, research suggests that sleeping with the TV on may negatively impact health in several ways:
- Light, especially blue light, suppresses melatonin and delays the circadian rhythm
- Noise from the TV can impair sleep quality
- Exciting content before bed can make it harder to fall asleep
- Sleeping with the TV on may exacerbate insomnia
- Poor sleep from TV exposure may increase the long-term risk of heart disease, diabetes, obesity, and premature death
Setting a pre-bedtime media curfew, removing TV from the bedroom, and practicing good sleep hygiene can help break the cycle of increased television and sleep disruptions.