Daily Screen & Blue-Light Cut-Off Planner
Turn your bedtime into a daily screen cut-off time
Screen cut-offs, blue light and common questions
Why plan a specific screen and blue-light cut-off time?
A clear cut-off makes it easier to keep evenings calmer and more sleep-friendly. Instead of scrolling until you are exhausted, you pick a time to park bright screens, dim lights and switch to offline wind-down habits. That can support melatonin, circadian rhythm and a faster slide into sleep.
How does blue light affect melatonin and sleep?
Light of any colour can delay melatonin, but blue-rich light from LEDs and screens does it more strongly. Experiments show that blue light in the evening can suppress melatonin for longer and shift the body clock more than other wavelengths, which can make it harder to fall asleep on time.
How long before bed should I stop using screens?
Different sources suggest different ranges. Some sleep-hygiene advice recommends turning off electronic devices at least 30 minutes before bed, while other experts suggest aiming for 1–2 hours without bright, close-up screens, especially if you already struggle with falling asleep.
Do I have to be perfect and never look at a screen after cut-off?
Perfection is rarely realistic. Treat the cut-off as your default rule and try to stick to it most nights. If you occasionally need to check something, dim the screen, use night modes, keep it brief and avoid starting long, emotionally intense or work-heavy tasks.
Do “night mode” and blue-light filters replace a cut-off time?
Warm-colour modes, dark mode, blue-light-filter glasses and e-ink screens can all help make evening use less intense, but they do not fully remove alerting light or mental stimulation. A firm cut-off plus softer lighting and calmer activities usually works better than filters alone.
What if my schedule changes (shifts, parenting, travel)?
Shift work, caring for children, travel and health conditions can all make a fixed cut-off hard. You can still plan a buffer relative to whatever your current target bedtime is, then adjust the rule when your schedule changes, rather than giving up on the idea entirely.
When should I talk to a clinician about sleep instead of just changing screens?
Reach out for medical or psychological help if you have long-term insomnia, very loud snoring, breathing pauses in sleep, restless legs, extreme daytime sleepiness, mood changes or safety concerns. Screen habits matter, but many sleep disorders need proper assessment and treatment.
How to use this daily screen and blue-light cut-off planner
This planner turns “I should get off my phone earlier” into a concrete time you can see on the clock. You choose your usual bedtime and how much screen-free time you want before it, and the calculator returns a screen and blue-light cut-off time you can use every day.
1. Pick the bedtime you are actually aiming for
Add the time you would like to have lights out and be trying to sleep on a typical night, using the 24-hour format (for example, 22:30 for 10:30 pm). It does not need to be perfect; just pick the bedtime you want to design your evenings around.
2. Choose a realistic screen-free buffer
Next, type how many hours you want to be off bright screens before bed. Many people start with 0.5–2 hours and adjust from there. A shorter buffer is easier to begin with; a longer one may be more helpful if you are very sensitive to light or tend to get “pulled in” by late-night content.
3. Read your daily cut-off time
When you tap Plan daily screen cut-off, the tool shows:
- Your chosen bedtime in 24-hour format.
- Your screen-free buffer in hours.
- A screen and blue-light cut-off time based on those numbers.
- Whether that cut-off falls on the same calendar day or the previous one.
The planner assumes you keep roughly the same bedtime most days. If your schedule changes a lot, you can rerun the calculation with a different bedtime and buffer.
4. Use the note and summary to make it real
The note field lets you tag the rule (for example, “weeknights only”, “days before early shifts” or “for exam season”). That note appears in the copyable summary, so you can paste the rule into a calendar, phone reminder or habit-tracking app.
Try pairing the cut-off with specific alternatives: reading, stretching, planning the next day, chatting with someone you live with, or listening to audio with the screen turned off. It is easier to respect the buffer when you know what you are doing instead of scrolling.
How the screen cut-off time math works
Under the hood, the planner uses very simple arithmetic so you can check it on a normal clock or calculator. The goal is clarity, not complicated modelling of sleep biology.
1. Convert bedtime to minutes after midnight
First, the time you enter is converted into minutes after midnight. For example, 22:30 is treated as 22 × 60 + 30 = 1 350 minutes.
2. Convert your buffer into minutes
Next, the buffer you enter in hours is turned into minutes:
Buffer minutes = Buffer hours × 60
A 1.5 hour buffer becomes 90 minutes, a 0.75 hour buffer becomes 45 minutes, and so on.
3. Subtract the buffer from your bedtime
The planner then subtracts the buffer minutes from the bedtime minutes:
Cut-off minutes = Bedtime minutes − Buffer minutes
If this is still above zero, the cut-off falls on the same calendar day. If it dips below zero, the tool adds 24 hours (1 440 minutes) and marks the cut-off as belonging to the previous day.
4. Turn minutes back into a clock time
Finally, the minutes value is converted back to a 24-hour time like 20:45 or 21:30 and shown in the result card and summary table, along with your bedtime and buffer. The numbers are rounded to the nearest minute to keep things neat.
Because evening light, stress, caffeine, exercise and health conditions all affect sleep, the planner should be seen as a simple boundary helper. If you are experimenting with stricter cut-offs, light boxes, tinted glasses or therapy for insomnia, follow the protocol from your clinician or sleep specialist.
References and further reading on blue light, screens and sleep
These resources discuss how evening light and screen use affect melatonin, circadian rhythms and sleep quality:
- Harvard Health Publishing — Blue light has a dark side — explains how blue light in the evening suppresses melatonin more strongly than other wavelengths and can shift the body clock.
- Sleep Foundation — Blue Light: What It Is and How It Affects Sleep — describes what blue light is, how it influences alertness and sleep cycles, and practical ways to reduce exposure before bed.
- Centers for Disease Control and Prevention — About sleep and sleep hygiene — outlines basic sleep-habit advice, including keeping bedrooms relaxing and turning off electronic devices before bedtime.
Use these as general background and combine them with personal guidance from your healthcare team, especially if you have chronic insomnia, shift-work sleep issues or other medical questions about light and sleep.