ASAKUKI Essential Oil Diffuser for Home, 500ML Aromatherapy Humidifier

The ASAKUKI 500ml is one of the most-reviewed essential oil diffusers on Amazon, with a 4.3-star average from around 72,400 reviews. It costs about $29.

The features that matter at bedtime

The tank holds 500ml of water. That's larger than many small diffusers, so it can run longer between refills. It's ultrasonic, meaning it turns water and a few drops of oil into a fine mist instead of heating it.

For sleep, three things matter:

• The light and mist work separately, so you can switch the LED off and keep the mist running. There are seven light colors if you do want a nightlight.
• Timers run for 60, 120 or 180 minutes, or the diffuser stays on. You can also set an intermittent mist. A timer means it isn't running all night.
• It switches itself off when the water runs out.

A remote works from up to 16.5 feet, so you can change settings without getting out of bed. ASAKUKI claims the fan runs below 23 dB. We'd treat that as a quiet-but-not-silent guide rather than a lab figure, and light sleepers may still hear it.

What it won't do

A diffuser makes your room smell of whatever oil you put in it. Some people find a familiar scent like lavender part of a calming routine, and that's a fair reason to buy one. It isn't a sleep treatment. Our bedtime routine for adults explains how a scent cue fits into a wind-down, and how to stop racing thoughts at night covers sensory anchoring.

The listing says the BPA-free plastic is safe for babies and pets. That's about the plastic, not the oils you put in it. If you have pets or a baby at home, check with your vet or pediatrician before diffusing essential oils around them.

Who it's for

• People who want scent as part of a regular wind-down routine
• Anyone who wants a timer and a light that turns off completely

Who should skip it

If you only want a scent on your pillow, the This Works Deep Sleep Pillow Spray does that without water, cleaning or a device on your nightstand. It's about $33 for 2.5 fl oz.

Light sleepers who need total silence may also want to skip a diffuser. A white noise machine is a different way to calm a noisy mind at night.