Screen Time Before Bed: What the Data Actually Shows

"No screens before bed." It's one of the most repeated pieces of sleep advice. But is it actually true for you?

The relationship between screen time and sleep is more complicated than headlines suggest. Blue light matters—but so does mental stimulation, individual sensitivity, and what you're actually doing on that screen.

Here's what the data actually shows, and how to figure out if screens are affecting your sleep.

The Blue Light Hypothesis

The concern about screens centers on blue light.

Your body uses light to regulate your circadian rhythm. Blue light, which is prevalent in screen emissions, signals "daytime" to your brain. Exposure to blue light in the evening can suppress melatonin production and delay your body's readiness for sleep.

What research shows:

• Blue light does suppress melatonin
• The effect is measurable in lab conditions
• Evening screen use correlates with later bedtimes and shorter sleep

But also:

• The effect size varies significantly between individuals
• Modern devices emit less blue light than older ones
• Night modes and filters reduce blue light exposure
• The content you consume may matter more than the light itself

Key Insight: Blue light affects melatonin, but that doesn't automatically mean it affects your sleep quality. Individual variation is huge.

Beyond Blue Light: Mental Stimulation

Blue light is only part of the story. What you do on screens matters too.

Stimulating content:

• Social media (emotional engagement, infinite scroll)
• Work emails (stress, mental activation)
• News (anxiety, rumination)
• Video games (adrenaline, alertness)
• Exciting movies/shows (emotional arousal)

Less stimulating content:

• E-reading (similar to physical books)
• Calm entertainment (relaxing shows)
• Light browsing

Someone reading an e-book might sleep better than someone doom-scrolling Twitter, even with the same blue light exposure.

What to Track

To understand your personal screen-sleep relationship, track:

Screen Time Inputs

Whether you used screens: Yes/no in the hour before bed

What type: Phone, tablet, computer, TV (different exposure levels)

What content: Stimulating vs. relaxing

Duration: 10 minutes vs. 2 hours has different effects

Whether you used night mode/filters: May reduce blue light impact

Sleep Outcomes

Sleep quality rating: 1-10 scale

Time to feel sleepy: Did you feel ready for sleep at your sleep opportunity?

Next-day energy: May reveal effects you don't notice consciously

Patterns to Look For

After two weeks of tracking, analyze:

Pattern 1: Clear Negative Effect

"When I use screens in the hour before bed, my sleep quality is consistently lower."

Screens affect you. Consider reducing or changing your evening routine.

Pattern 2: Content Matters

"Social media affects my sleep, but streaming a calm show doesn't."

The stimulation, not the blue light, is your issue. Adjust what you consume, not necessarily whether you use screens.

Pattern 3: Duration Matters

"Quick checks are fine, but extended scrolling affects me."

You have a threshold. Figure out where it is.

Pattern 4: No Clear Effect

"I don't see a correlation between screen time and sleep quality."

Either screens don't affect you much, or other factors are more important. Keep tracking other sleep inputs.

Pattern 5: Delayed Effect

"I fall asleep fine after screens, but wake up during the night more."

Blue light might be affecting your sleep architecture without affecting sleep onset. Track nighttime awakenings.

Running an Experiment

Want definitive answers? Run a controlled test:

Week 1: No Screens Before Bed

For 7 days, commit to no screens in the hour before your sleep opportunity. Read a physical book, do light stretching, or other non-screen activities.

Track:

• Sleep quality each night
• Time to fall asleep
• How difficult it was to avoid screens

Week 2: Normal Screen Use

Return to your typical evening screen habits.

Track the same metrics.

Compare

Is there a meaningful difference? How big? Is the improvement worth the behavioral change?

Practical Strategies

If screens do affect your sleep, options include:

Reduce Blue Light

• Enable night mode on devices (iOS Night Shift, Android Night Light)
• Use apps like f.lux on computers
• Wear blue light blocking glasses (effectiveness debated)
• Reduce brightness

Reduce Stimulation

• Avoid social media before bed
• Don't check work email
• Choose calm content over exciting content
• Set "wind down" time limits in device settings

Create Transition Time

Instead of screen → bed, try:

• Screen → 15 minutes of reading → bed
• Screen → light stretching → bed
• Gradual dimming of all lights

Replace Screen Time

What would you do instead?

• Read a physical book
• Listen to a podcast or audiobook
• Practice meditation or breathing exercises
• Prep for tomorrow
• Connect with a partner

The TV Exception

TV is often treated differently than phones/tablets:

Arguments that TV is better:

• Farther from your eyes (less intense blue light)
• Passive watching (less mentally stimulating than scrolling)
• Often watched in dim rooms

Arguments that TV is also a problem:

• Still emits blue light
• Can be stimulating depending on content
• May delay bedtime ("just one more episode")

Track TV separately from phone/tablet use to see if they affect you differently.

Common Questions

Does reading on a Kindle count?

E-ink displays (like basic Kindle) don't emit blue light the same way backlit screens do. They're closer to reading a physical book. Backlit tablets (like Kindle Fire) are more like phones.

Will blue light glasses help?

Research is mixed. They reduce blue light exposure but studies on sleep improvement show inconsistent results. Track your sleep with and without them to see if they help you.

What about morning screen time?

Morning screen use might actually help—bright light in the morning signals "wake up" to your circadian rhythm. The concern is primarily about evening use.

How long before bed should I stop?

Standard advice is 1-2 hours. Your tracking will reveal your personal threshold. Some people are fine with 30 minutes; others need 2+ hours.

What to Track in Trendwell

Input	Why It Matters	How to Log
Screens before bed	Main input	Yes/no in last hour
Screen type	Different intensities	Phone/tablet/TV/computer
Content type	Stimulation matters	Stimulating/calm
Night mode	May reduce impact	Whether you used it
Sleep quality	Outcome to correlate	1-10 rating

Next Steps

• Read: The Complete Guide to Sleep Inputs
• Read: Sleep Opportunity: The Metric You Can Actually Control
• Read: How to Find Your Ideal Bedtime Through Tracking
• Start tracking: Get started with Trendwell

The question isn't "do screens affect sleep?" The question is "do screens affect your sleep?" Track, experiment, and find out.

---

Last updated: January 2026