Your Night-and-Day Guide to Staying Cool (Without AC)

This article was originally published in 2022 and has been updated to include new research with around the clock tips.

We’ve all been there. A sudden summer heatwave rolls in, the air turns into a sauna and you realize your apartment doesn’t have air conditioning or the machine has just died. Getting out for work or down for a good night’s sleep ends up feeling like an Olympic sport.

That said, I often hear that hot weather makes it difficult to work and sleep. Keeping your cool in a heatwave isn’t just about what you do when your body starts to overheat. To beat the heat, you need to manage your body temperature and your environment 24/7.

Here’s your science-backed, AM-to-PM guide for surviving a heatwave and getting some cooling relief — no AC required.

The A.M. list: daytime prep to keep temps low

Winning the battle against heat starts the moment the sun comes up. Using these morning and afternoon strategies will prep your body and your home.

1. Execute a morning blackout

Before you head out the door or log on to work, close your windows, blinds, and curtains. About 30% of unwanted heat enters your home through your windows. By blocking the greenhouse effect early in the day, you trap the cooler morning air inside and keep the midday solar radiation out.

2. Practice “precooling” before peak heat

If you have to be active or step outside during the day then don’t wait until you’re overheating to try and cool down. It turns out “precooling” (a.k.a. actively lowering your body temp before heat exposure) drastically improves how well your body regulates its temperature as the day goes on.

How you can do it: Sip iced drinks or apply a cold, damp towel to your neck and wrists before you start feeling miserably hot. Just be careful not to cool yourself down too much or on muscles you’re actively about to use.

3. Eat light and lean (and ditch the heavy meals)

Your body generates heat just by digesting food. So when you eat massive, protein-heavy meals or greasy comfort foods they require a ton of energy to break down and cause your internal thermostat to spike. Stick to lighter, water-rich foods during a heatwave — think salads, grilled chicken, fruit smoothies and chilled soups.

4. Hydrate for sweating efficiency

Sweat is your body’s built-in AC, but it only works if you’re properly fueled. Drink water consistently throughout the day so your body has the fluid reserves it needs to sweat efficiently when you’re trying to cool off later. Just be sure to taper off your liquid intake about two hours before bed so you aren’t waking up for middle-of-the-night bathroom trips.

5. ‘“MacGyver” some free AC

While the infamous MacGyver never rigged up an air-conditioning system (that we know of), he could have with nothing but a fan and a bunch of ice packs or frozen water bottles. Place the frozen items about six inches in front of the fan and hey presto: free AC! 

As the ice melts the fan will pick up the chilled air to create a cool, refreshing breeze that mimics a premium swamp cooler. Rotate items back in the freezer so you’re ready for the next session. 

The P.M. list: nighttime tactics for deep sleep

Don’t let the heat disrupt your sleep. When the sun goes down, it’s time to optimize your sleep environment and trick your body into a state of deep, cool relaxation. 

6. Deploy the “3x cooling formula”

Don’t just turn on a fan and hope for the best. To cool a room without AC you need to combine low-energy air movement with the right fabrics.

Combining low-energy airflow (like a standard pedestal or ceiling fan) with lightweight, breathable bedding seriously reduces nighttime heat. This combo is three times more effective at keeping you cool than just using a fan alone.

So, strip your bed down to a single 100% cotton or bamboo top sheet, ditch the polyester blends and set up your fan to keep air circulating across the bed.

7. Avoid the over-cooling trap

While you want a good breeze to fall asleep, blasting a high-speed fan directly at your face all night can actually backfire.

Because our bodies can’t actively adjust our blankets or clothes while we sleep, continuous high-speed direct airflow can cause core body temperatures to drop too low in the early morning. This sudden drop triggers a mild stress response, disrupts your immune system and wakes you up.

Be sure to set your fan to an oscillating setting on a low or medium speed. This keeps the air in the room moving without constantly shocking your body with direct, high-velocity wind while you sleep.

8. Take a lukewarm (not freezing) shower before bed

A freezing cold shower sounds amazing when you’re sweating but it actually causes your blood vessels to shrink, trapping heat inside your core. Instead, take a lukewarm shower. As you step out into the room the water will evaporate off your skin, naturally mimicking your body’s natural trigger for sleep. Making for a gradual drop in core temperature.

9. Stroll before sleep

Instead of staring at a screen, take 30 minutes to enjoy the long summer days by taking a pre-bed stroll. It’s a great way to wind down and make the most of warm summer evenings. You’ll miss them when they’re gone!

10. Let darkness reign

The human body is programmed to wake when it’s light and sleep at night. To prevent interruption of this natural sleep cycle, keep your bedroom dark with heavy curtains and cover the LED lights in your electronics; even before the sun goes down during those longer days.

10. Go dark before bed

Another advantage of an evening walk is that spending time in a darkened environment, indoors or out, gives your mind and body the cue that it’s time for slumber. Chilling on an unlit porch, patio, or deck is another great way to savour the season and put your mind at ease.

What to remember

All you really need to know is that you’ve got a whole toolbox of ways to keep your cool. So this summer, be sure to keep an eye on the forecast and have the strategies that work best for you ready!