Almost half of Aussie adults snore and it's not only men.

But regardless of who's making the nocturnal rumblings, experts warn it's important not to ignore one of the telltale signs of sleep apnoea.

Friday is World Sleep Day and health specialists are using the date to appeal for greater awareness of sleep apnoea, a condition believed to affect three million Australians - but 80 per cent of them don't realise.

"Sleep apnoea can go undetected for years," ResMed sleep analyst Carmel Harrington said.

"Therefore, many are not aware they have the condition but wonder why they wake up feeling unrefreshed and with no energy."

Ongoing poor-quality sleep can cause more significant health conditions including elevated blood pressure and heart disease, Dr Harrington said.

"If you snore, have been told you stop breathing in your sleep, or feel tired each day despite getting enough hours of sleep, sleep apnoea - which is treatable at home - could be the cause," she added.

Other than snoring, sleep apnoea symptoms can include daytime tiredness, mood swings, headaches and restlessness.

Diagnosis and treatment of sleep apnoea is simple and people should seek medical advice.

Global health and technology organisation ResMed's latest Australian sleep survey of more than 2000 people found that 47 per cent of respondents admitted snoring. Almost half (45 per cent) of women surveyed snore, and 49 per cent of men.