Chilisleep ooler review: Will it improve your sleep?

Setting it up

The ooler comes in a cleverly designed box, with all the reverse origami and neat experience of something such as an Apple product. Everything is stowed away in its own compartment, which not only makes for an aesthetically pleasing experience but also makes it easier to understand where everything should go.

The system is made up of three parts: a mat that goes underneath your bedsheet, on top of your mattress; a unit that disperses the water and heat to make everything work, and tubes that connect the other two components.

Chilsleep, the company that produces the unit, doesn’t make its naming systems entirely simple. The unit we reviewed is called the ooler, and there is another one called the cube, while the mesh that goes under the bedsheet is called a chilipad.

It’s worth noting the ooler unit itself is fairly chunky – about the size of a printer – but with most beds, it should hide away easily underneath. However, if you happen to have under-bed storage, like I do, you might have to find somewhere else to stash the ooler unit.

Once you’ve put the mat onto your bed, found a spot for the unit, connected it all together and plugged it in, you fill up the machine with water, so it can circulate and help cool you down. With that done, you’re ready to start chilling.

In use

You’ll feel the benefit of the ooler as soon as you get into bed – if it’s been on for long enough, your sheets will feel as if they’ve been in the fridge. That pleasant chill passes quite quickly as your body cools down, but the benefits don’t end there.

Through the night, the ooler whirrs away, taking away the heat from your body and swapping it for cool water. The whirr is very perceptible – Chilisleep admirably sell it as being like a white-noise machine, and you can change the intensity, but you won’t forget the machine and its fan are busy getting to work underneath your bed.

Even using the unit, sometimes it was still too warm, but that is no fault of the ooler – only on the hottest nights was it still unpleasant, and it was certainly less unpleasant than it would have been without the machine.

One potential problem with the chilipad is that, if you don’t have great airflow in your bedroom, there is nowhere for the heat to go after it is channeled out of your bed – it will just hang around, not in your bed but somewhere else in the room. Sometimes, I would get out of bed to feel hot air blasting out from the unit. Obviously it’s better for that hot air to be somewhere else than in your sheets but it is perhaps best paired with an air-conditioning unit for the bedroom, too, so the heat can actually leave rather than get shunted around.

Another issue is energy: the unit is rated around ~500kWh/year, according to Chilisleep. That’s about the same as appliances such as a fridge – though, of course, it isn’t on all the time.

The ooler’s energy usage is likely to be concerning for two reasons. First, it can be expensive, especially as energy bills shoot up, and using electricity on staying cool like this can feel a little too much like a luxury. Secondly, it means you are contributing to the warming of the planet, while trying to avoid the effects of a hotter climate.

It is a frustrating situation, and the answer to it lies outside the scope of this review. But it is certainly worth working out how much using the ooler is likely to cost you, both financially and morally, and whether that will be worth it.

App

The ooler is controlled by its own mobile app, for iOS and Android, which connects to the unit via bluetooth and lets you make whatever changes you need. There are also buttons on the unit itself, though they are limited and hard to press, especially if you’ve tucked it away.

You can choose just how intensely it runs: there are three options, between “boost” and “silent” (which isn’t), which enable you to compromise between noise and intensity of cooling. You can also set the target temperature, though, through the UK summer, it was mostly academic, since the unit was stuck in a tragic tussle with the hot London night.

The app also includes a “warm awake” feature, where the system essentially goes into reverse, slowly warming up the temperature so that you wake up naturally and without an alarm clock. It works perfectly: I woke up softly at the right time every day. The unfortunate thing was that I also woke up warm and bathed in my own sweat, which was less pleasant. I eventually turned the feature off, and it stayed that way.

Sleep performance

The important thing, of course, is how well you actually sleep, and the short answer is: very well.

Temperature is absolutely key to sleep. Being hot at night doesn’t only mean you wake up in a frustrating puddle of sweat, it also keeps your body from doing what it needs to – that’s why you can feel sleepy when it gets colder in the evening, and why you might stick your arms and legs out of the sheets involuntarily.

So, getting the temperature right is key to having a good sleep, too. Thankfully, the ooler is clearly a winner on this point. While it could do more – the limitations of the unit mean you aren’t always as cold as you’d like, even if it is doing a fantastic job of getting you cooler – the chilling effect is enough to make a clear difference to your sleep.

I could see that in how I felt in the morning. I woke up more refreshed, more relaxed and, importantly, without a sheen of sweat.

But I could also see it in the numbers I tracked through the time I used the ooler. If I didn’t switch it on during a warm night, both Garmin and Whoop trackers showed a clear reduction in the amount and quality of sleep, as well as important measures of how rested I was, such as heart rate variability.

In short, the ooler worked at getting me to sleep, better than I ever had before. It could have worked better – but then it’s not possible to imagine a gadget that could make a hot, horrible summer night in a London flat a genuinely non-warm experience.

Currently on offer at £399.50, the ooler sleep system with chilipad usually retails for £799.