Their annoying chirping can wake you up far earlier than you'd like – no, not some nocturnal animal, a smoke alarm with a flat battery!
Paul Smith of consumer.org.nz has been testing smoke alarms to see which ones respond fastest to smouldering and flaming fires.
His findings – "not all smoke alarms are created equal".
So which ones work best and which ones should be avoided at all costs to keep your family safe?
"We recommend you choose photoelectric alarms. The New Zealand Fire Service recommends photoelectric alarms. The Residential Tenancy Act requires landlords to replace expired smoke alarms with long-life battery photoelectric smoke alarms. We think ionisation alarms should not be sold in New Zealand."
Paul also has some handy tips on the best places to install smoke alarms in your home to minimise the nuisance alarms which can lead some people to abandon smoke alarms altogether.
"Nuisance alarms aren't just a response to burning toast. They can also be caused by high humidity, dust and insects... None of the alarms in our test could tell the difference between real and nuisance smoke. In general, the best alarms at ignoring nuisance sources were also the worst at responding to real sources."