💚 Group C
Phase 3 — Investigation
🩺 Interactive
⏱ 15 minutes
Task 6 — The Health Advocate
Investigate blue light, eye strain, sleep disruption and healthy screen habits using the Screen Time Impact Simulator. Use AI to research, then fact-check one claim against a trusted source.
Step 1 — Read before you start
Group C — Screens & Eye Health
Read or listen to this before the interactive tools unlock
Screens are useful, but long periods of screen use can affect comfort and wellbeing. Too much screen time may contribute to eye strain, tired eyes, headaches, and sleep disruption — especially when screen use continues close to bedtime.
Blue light is one factor discussed in research. Screens emit significant amounts of blue-wavelength light, which is the same range that stimulates the S-cones in your eye. Blue light signals to the brain that it is daytime — which can suppress the production of melatonin, the hormone that makes you feel sleepy.
However, blue light is not the only factor. Brightness, distance from the screen, posture, length of use, and whether you take regular breaks all play a role in how screen use affects your eyes and wellbeing.
Blue light is one factor discussed in research. Screens emit significant amounts of blue-wavelength light, which is the same range that stimulates the S-cones in your eye. Blue light signals to the brain that it is daytime — which can suppress the production of melatonin, the hormone that makes you feel sleepy.
However, blue light is not the only factor. Brightness, distance from the screen, posture, length of use, and whether you take regular breaks all play a role in how screen use affects your eyes and wellbeing.
⚖️ Balanced science: Screens do not automatically damage eyes in the short term — but unhealthy habits can increase discomfort and affect sleep. Your job as a Health Advocate is to present the evidence fairly, not alarmingly.
blue light
melatonin
eye strain
circadian rhythm
Step 2 — Screen Time Impact Simulator
📊 Drag the slider to explore how screen time affects your body
Try to find the point where each indicator starts to change. The scale is 0–10 hours of daily screen use.
Low
Eye Strain Level
At this level, your eyes are comfortable. The muscles that focus your lens are not significantly fatigued.
Normal
Melatonin Level
Melatonin production is normal. Screen use at this level has limited impact on your sleep hormone.
Good
Sleep Quality
Sleep is unlikely to be disrupted at this level — especially if you stop screens at least 1 hour before bed.
The NHS recommends taking regular screen breaks throughout the day. At 4 hours of daily screen use, occasional discomfort is possible but not inevitable — especially if you follow the 20-20-20 rule.
🔍 Challenge — Find the Tipping Points
Drag the slider slowly from 0 to 10 hours. At what screen-time value does each indicator first change from green to amber? Note your findings below, then reveal the answers.
👁 Eye strain turns amber at ~3.5 hours — sustained focus for this long fatigues the ciliary muscles. |
🌙 Melatonin starts dropping at ~4 hours — especially if evening screen use is included. |
💤 Sleep quality declines noticeably at ~5–6 hours of total daily screen use.
Step 3 — Healthy Screen Habits
✅ Which habits do you already practise?
Tap any habit to mark it as something you do. Save your choices to your portfolio.
Take regular breaks
Every 20 minutes, look at something 20 feet away for 20 seconds (the 20-20-20 rule). This relaxes the ciliary muscle.
Reduce screens before bed
Stop using screens at least 1 hour before sleep. Blue light suppresses melatonin and delays how quickly you fall asleep.
Keep your distance
Hold your device at least 35–40cm from your face. Screens held very close require more effort from your eye muscles.
Remember to blink
Screen users blink up to 60% less than normal. Blinking spreads tears across the eye, keeping it moist and reducing dryness.
Adjust brightness & night mode
Reduce screen brightness in the evening. Many devices have a night mode that reduces blue light emission after sunset.
Change focus & move
Every hour, stand up and look out of a window (far focus). Physical movement also helps reset your posture and reduces neck strain.
✅ Saved!
Step 4 — AI Research & Fact Check
🤖 Wonder Learning AI — Group C
Generate an AI explanation, highlight one sentence, then fact-check it against a trusted source
Pre-loaded prompt (editable)
"What does science say about blue light from screens? Give healthy screen habits for teenagers, with one surprising fact."
🔍 Fact-check this statement
Select a sentence above to fact-check it.
Verify against a trusted source:
🏥 NHS Eye Health
😴 Sleep Foundation — Blue Light
🌍 WHO Digital Health
My verdict:
✅ Fact-check saved to your portfolio!
Bridge to Phase 4
"You have explored the science of how screens affect the eyes and brain. When you present in Task 9, share the habit you think is most important — and the one AI claim you verified."
What happens in Task 6
Group C investigates how screens affect physical health and sleep. After reading the intro and tapping "Mark as understood", students use the Screen Time Impact Simulator (0–10 hour drag slider showing 3 animated health indicators with science sentences per level), a 6-habit interactive checklist, and an AI research panel with sentence-level fact-checking. A mid-investigation quiz auto-triggers at 10 minutes for all groups simultaneously.
📋 Learning objectives
- Understand the health effects of prolonged screen exposure on the eyes and brain
- Identify evidence-based strategies for healthy screen use
- Use AI tools critically — generating content and verifying one claim against a trusted source
🔑 Key terms
blue light
melatonin
eye strain
circadian rhythm
ciliary muscle
20-20-20 rule
♿ SEN Adaptations
- Simulator slider uses a large touch target with a high-contrast thumb
- All tooltips available as read-aloud (speaker icon)
- Poster builder has a simplified template with fewer layout options
- Science sentences read aloud on tap
- Habit checklist uses large tap targets
- Output assessed on process engagement, not volume or length
🖨️ No-Tech Format
- Printed "Screen Habits" survey template — students fill in daily habits and calculate weekly totals
- Two printed source article excerpts (NHS + Sleep Foundation)
- Blank poster template to complete by hand
- Teacher describes the simulator indicators verbally as a class discussion
🔬 Extension (ages 13–15)
- Research the difference between short-term and long-term effects — what does longitudinal research show?
- Interview a family member about how their screen habits have changed and what they notice about their sleep
- Explore how blue light filters (Night Shift / Night Mode) actually work — do they significantly reduce S-cone stimulation?