Can foil really keep you cool at night? I tried it and it transformed my attic bedroom (and sleep)

I sleep in an attic bedroom, which can get awfully hot during the summer months as sun blears in through the roof windows and heat rises up the stairs.

To make sure I'm still getting good rest through summer, I sleep on one of this year's best cooling mattresses and maintain good sleep hygiene, but I'm also keen to test out DIY cooling hacks doing the rounds on social media to see if they're really worth your time.

Last week I put homemade air con to the test (it works but I wouldn't recommend it for night-long cooling). This week I'm duct taping aluminium foil to my bedroom window — there's never a dull moment as a sleep writer. Here's how I kept my room cool with this $4 cooling hack...

How I slept after using the foil cooling hack

Employing the caveman method, I usually close my blackout roller blinds during hot days to block out the sun blaring in through my skylight windows and (attempt to) keep my attic bedroom cool.

So I was intrigued to see whether foil could work as well, or better, than my slightly worn-out blinds.

I constructed my DIY blackout blind set-up early in the morning before starting work for the day. When I returned to my bedroom in the evening, it was noticeably cooler than it would have been had I left the sun's rays spill in all day.

I would even say my room was cooler with the foil rather than blinds, likely due to its reflective quality.

The foil's shiny surface and thinness prevents it from absorbing heat itself, instead bouncing it back and making it effective at blocking heat transfer. Admittedly, my black out blinds are years old and don't have a reflective surface.

Although my bedroom was cooler, it wasn't quite cool enough to wrap up in the covers. But with one leg under the duvet and one leg out (the ideal sleep position, if you ask me) I had no trouble drifting off to sleep.

My Oura Ring reckons it took me 5 minutes to fall asleep and I scored 85% for sleep efficiency that night, suggesting I got a peaceful, uninterrupted night of rest after using this bedroom cooling hack.

All in all, it gets my sign of approval.

How to set up your foil blinds

The foil cooling hack is pretty simple — you cover up your windows with aluminium foil, available from $1.68 at Walmart, stopping light and hot sun rays getting into your home.

You can hold the foil in place by spraying water on your windows so the foil sticks to them, or securing it with duct tape. I used the latter method.

I only have one small window in my bedroom so I could set it up in a matter of minutes, but imagine it would be time-consuming and tedious with larger/more windows.

Anyhow, the key to getting the best benefit from this cooling hack is foiling your windows early in the day before the sun gets too hot, so that by the time you get into bed no hot rays have entered your room.

With a little preparation and organisation, this hack can keep your bedroom a cool haven all day long rather than you having to go through the faff of setting up DIY air cons and the like to cool it down at bedtime.

Verdict

Whether I'll have the time and effort to duct tape up my windows every summer day is questionable as it's far easier to zip down my blinds even if they don't provide the same cooling power.

But if you're looking for a cheap, reasonably quick bedroom cooling solution, I certainly recommend the tin foil hack. My bedroom was noticeably cooler and I was able to drop off without tossing and turning in a sweaty fluster.

This hack can also be used to block out light, helping you get young children off to sleep on lighter summer evenings, or help you sleep in through the summer break, without having to fork out on new blinds.

(However, if you do have the budget, there are plenty of blackout blinds and curtains available at Amazon with prices starting around $20.)

While the foil cooling hack cross caveman method works for me, it's not a one-size-fits-all approach to cool sleep. For example, my colleague Ruth didn't like the caveman method as it threw her circadian rhythm out of whack.

Essentially, it's worth trying different hacks and cooling products to find the right one for your sleep needs and lifestyle. Things as simple as shifting your evening meal earlier, taking a lukewarm evening shower and stretching before bed can all help you cool down to optimal sleep temperature at night.

Plus, especially hot sleepers may need more robust and personal cooling systems to sleep well all year round. If hot sleeping is a persistent issue, I recommend checking out temperature-regulating technology offered by the best smart beds online right now (just beware a big budget is required).