Most "blackout" curtains aren't blackout. They're room-darkening at best, blocking maybe 85-90% of light and leaving enough glow around the edges to keep your brain from producing the melatonin it needs for deep sleep. Only 28% of Brits get seven or more hours per night. Light in the bedroom is one reason, and curtains are usually the first fix people try.
We've compared the main types of blackout curtains available in the UK to see which actually deliver near-total darkness and which are marketing the word "blackout" loosely.
Why blackout matters for sleep
Light suppresses melatonin. Even small amounts. Your eyelids block most visible light, but the 1-5% that gets through is enough for the photoreceptors in your retina to detect. Streetlights, car headlights, and summer dawn all register while you sleep. The result: shallower sleep, less time in the restorative stages, and that tired-but-wired feeling in the morning.
Our article on sleep masks and light covers the science in detail. The short version: proper darkness isn't optional for good sleep, it's the foundation.
Types of blackout curtains
Thermal blackout curtains (eyelet)
The most popular option on Amazon UK. Eyelet (ring-top) curtains with a foam-backed blackout lining that also insulates. They hang from a curtain pole and are easy to open and close.
The eyelet holes are the weak point. Each ring creates a small light gap at the top of the curtain where the fabric gathers. In a dark bedroom, these show up as a row of bright spots along the pole. You can minimise this by choosing curtains wider than your window (allow at least 30cm overlap on each side) and hanging the pole higher and wider than the window frame.
Price: £20-45 per pair for a standard window.
Best for: living rooms, bedrooms where "very dark" rather than "total darkness" is acceptable.
Pencil pleat blackout curtains
Pencil pleat curtains gather at the top with a tape heading rather than eyelets. When hung from a track (not a pole), the heading creates a tighter seal across the top of the window with fewer light gaps than eyelets. The trade-off is that they look more traditional and don't slide as smoothly.
For maximum light blocking, pencil pleat on a ceiling-mounted track with a pelmet over the top is the best curtain-based solution. The pelmet blocks the gap between the track and the ceiling. Combined with curtains that are wide enough to overlap the wall on each side, this gets close to 99% light blocking.
Price: £25-50 per pair. Track and pelmet are additional.
Best for: bedrooms where you want the darkest possible curtain solution.
Tab-top and slot-top blackout curtains
Tab-top curtains hang from fabric loops. Slot-top curtains thread directly onto the pole. Both create more light gaps at the top than pencil pleat but fewer than eyelets. They don't slide easily, so opening and closing them daily is a minor annoyance.
Not widely recommended for bedrooms because the top seal isn't great and the sliding friction makes daily use irritating.
Blackout curtain liners
Separate linings that hang behind your existing curtains. They clip or hook onto the same curtain hooks and add a blackout layer without replacing your curtains. Useful if you like your current curtains but they don't block enough light.
The gap between the liner and the curtain can let light through at the edges. Not as effective as integrated blackout curtains but much cheaper than replacing everything.
Price: £10-25 per pair.
Portable blackout curtains (travel)
Suction-cup or Velcro-mounted panels for travel or temporary use. See our light blocking blinds article for the blind equivalents. Curtain versions use a tension rod and blackout fabric. Useful for children's rooms, guest rooms, or rented accommodation.
The overlap problem
This is where most people go wrong. They buy blackout curtains the exact width of their window. The curtains close in the middle but light pours in around all four edges.
Fix:
- Width: buy curtains at least 1.5x the width of your window. 2x is better for pleated styles.
- Sides: mount the pole or track 15-20cm wider than the window frame on each side.
- Top: mount the pole as high above the window as possible. A pelmet or curtain valance covers any remaining gap.
- Bottom: curtains should just touch the floor or puddle slightly. A gap at the bottom lets light in from underneath.
What to look for when buying
Look for three-pass or triple-weave fabric. This is the standard for genuine blackout: three layers of coating on the back. If the listing says "room darkening" rather than "blackout," it's probably not three-pass.
Check the backing colour. White or silver reflects light and heat. Black backing absorbs heat and can make south-facing rooms uncomfortably warm in summer. Most quality blackout curtains use a white or cream backing regardless of the front colour.
Weight matters. Heavier is generally better for light blocking. Hold the fabric up to a light source. If any light comes through, it's not true blackout.
If the curtains claim thermal properties, they should specify an R-value or energy rating. Some just slap "thermal" on the listing without any measurable insulation benefit.
Blackout curtains vs blackout blinds
Both block light. Different strengths.
| Blackout curtains | Blackout blinds | |
|---|---|---|
| Light blocking | Good (great with pelmet) | Good (great with side channels) |
| Edge gaps | Covered by overlap | Requires cassette/channels |
| Insulation | Better (air gap behind curtain) | Moderate |
| Aesthetics | Warmer, softer look | Cleaner, more minimal |
| Daily use | Easy to open/close | Easy to raise/lower |
| Cost | £20-50/pair | £15-80/window |
Many people use both: a blackout blind for the precise window seal and a curtain over the top for the edges, insulation, and look. This is the most effective light-blocking setup for a bedroom.
Our light blocking blinds for bedrooms guide has the blind-specific comparison. For shift workers who need total darkness during the day, our blackout blinds for shift workers article covers that scenario.
What about sleep masks?
A sleep mask is the cheapest and fastest fix. Put it on and the light is gone. But it only works for the person wearing it, it can shift during sleep (especially for side sleepers), and it doesn't address room temperature or partner light.
Curtains fix the room. Masks fix the individual. Do sleep masks help you sleep? Our article covers the research if you're deciding between the two.
Best case: blackout curtains for the room and a sleep mask in the bedside drawer for travel or backup.
Waking up in a dark room
One drawback of proper blackout curtains: your bedroom stays dark past dawn, which can make it harder to wake up. Your body expects increasing light in the morning to trigger cortisol.
A sunrise alarm clock fixes this. It simulates dawn by gradually increasing light before your alarm, giving your brain the wake-up signal that your curtains are blocking. The combination of blackout curtains and a sunrise alarm is probably the best sleep environment you can create without spending serious money.
Blackout curtains for children's rooms
Children are more sensitive to light during sleep than adults. A partially dark room is often enough to disrupt a toddler's nap or cause early waking. Blackout curtains in a child's room are one of the most common recommendations from health visitors and sleep consultants.
The same rules apply: go wider than the window, mount the pole higher, and use a three-pass blackout fabric. Portable blackout blinds are useful for the travel cot when visiting grandparents.
FAQ
What are the best blackout curtains in the UK? Look for three-pass blackout fabric, white/silver backing, and eyelet or pencil pleat heading depending on whether you use a pole or track. Pencil pleat on a track with a pelmet gives the darkest result. Specific brand recommendations change with stock and pricing, so check current Amazon bestsellers in the blackout curtain category.
Are blackout curtains worth the extra cost? Over standard curtains, yes. The price difference is usually £10-15 for the same window size, and the sleep improvement is measurable. Over room-darkening curtains, the difference is smaller and depends on how sensitive you are to light.
Do blackout curtains keep a room cool? White or silver-backed blackout curtains reflect heat and can reduce room temperature by a few degrees in summer. Black-backed curtains absorb heat and can make the room warmer. Thermal blackout curtains with an insulating layer work in both directions: cooler in summer, warmer in winter.
How do I stop light coming in at the sides of blackout curtains? Mount the pole or track wider than the window frame (15-20cm each side). Use a curtain hold-back or magnetic strips at the wall edge to pull the curtain flush against the wall. Or add a blackout blind behind the curtain for the window itself.
Can I machine wash blackout curtains? Most can go in the machine on a gentle cycle at 30 degrees. Check the label. Avoid tumble drying as the heat can damage the blackout coating. Hang dry.
Do I need blackout curtains and blinds? For a bedroom where sleep quality is the priority, using both gives the best result. The blind handles the window precisely, the curtain covers the edges and adds insulation. For most people, one or the other is enough.
