Good-quality sleep is a cornerstone of overall health. How well and how long you sleep influences your risk of a range of chronic conditions, including heart disease and type 2 diabetes.

Consistently sleeping less than 7 hours per night or experiencing poor-quality sleep significantly increases diabetes risk. Sleep is now recognised as an independent risk factor—even if you eat well, exercise, and maintain a healthy weight, insufficient sleep still raises your risk.

How sleep affects metabolism

Research shows sleep strongly influences insulin function. Even a single night of poor sleep can reduce insulin sensitivity, impairing the body’s ability to regulate blood glucose. After only four nights of restricted sleep, insulin signalling in cells can drop by about 30%. In one study, women who slept 90 minutes less per night for several weeks had a 15% increase in insulin resistance, with premenopausal women showing a 20% rise.

Poor sleep also disrupts hormones that control appetite and glucose metabolism. This can lead to higher blood glucose, reduced insulin effectiveness, and increased hunger hormones—causing cravings for high-fat, high-sugar foods and up to 20% higher calorie intake overall.

In short, improving sleep isn’t just about feeling rested—it’s a powerful way to protect your metabolic health and reduce long-term diabetes risk.

How much sleep do we need?

The Australian and New Zealand governments recommend:

• Adults 18–64: 7–9 hours per night
• Adults 65 and over: 7–8 hours of uninterrupted sleep

Sleeping less than 5–6 hours is considered short sleep and can harm heart health. Conversely, sleeping 1–2 hours above the recommended range (long sleep) has also been linked to heart problems, though this may relate to factors such as depression or chronic illness.

Why sleep timing matters

It’s not just the amount of sleep, but also when you sleep. Shift workers that sleep during the day and are awake at night face higher risks of cardiovascular disease, type 2 diabetes, obesity, stroke, and high blood pressure. Even with enough hours of sleep, disruption of the natural sleep-wake cycle raises health risks.

Studies show night shift workers have a 17% higher risk of any cardiovascular event and a 26% higher risk of coronary heart disease compared to day workers.

Recap

• Aim for 7–9 hours of good-quality, uninterrupted sleep each night
• Maintain consistent sleep timing where possible
• Recognise and manage chronic sleep problems, such as insomnia and sleep apnoea
• Improving sleep is a modifiable lifestyle factor that can significantly reduce diabetes risk

How common are sleep problems?

Sleep problems are widespread. In 2016, nearly half of Australian adults reported at least two sleep-related problems. Among Māori adults, 33% reported current sleep issues, compared to 26% of non-Māori adults—about 1 in 3 Māori and 1 in 4 non-Māori adults. Chronic sleep problems lasting more than six months affected roughly 25% of adults, with higher rates in Māori populations.

When to see a doctor

Ongoing sleep problems can seriously affect your health, including your heart. See your doctor if you experience:

• Persistent difficulty falling or staying asleep for more than a couple of months
• Daytime tiredness, sleepiness, or irritability despite enough time in bed
• Loud or chronic snoring, or observed pauses in breathing during sleep
• Waking up unrefreshed or restless
• Sleep problems affecting work, relationships, or daily life
• Symptoms of sleep apnoea, including chronic snoring, excessive daytime sleepiness, or high blood pressure
• Sleep difficulties alongside other health conditions, such as diabetes, depression, chronic pain, or heart disease

Treatment options

Treatment depends on the cause of your sleep problem and may include:

• Lifestyle changes and sleep hygiene improvements
• Cognitive Behavioral Therapy for Insomnia (CBT-i), a proven, effective treatment available through trained GPs, psychologists, or online programs
• Medical treatments, such as short-term medication or CPAP machines for sleep apnoea
• Referral to sleep specialists for complex cases

Early help matters: Untreated sleep problems can worsen over time and increase the risk of heart disease, stroke, diabetes, and mental health issues. Getting help early improves sleep and reduces these risks.

Where to find help

Start with your GP, who can guide assessment, treatment, or referral to a sleep specialist. Sleep specialists and clinics across Australia and New Zealand offer diagnostic sleep studies and tailored treatment plans.

For more information or to find a sleep specialist in Australia, contact Sleep Healthcare Australia: 1800 717 566 | info@sleephealthcare.com.au

Remember, good sleep is a cornerstone of good health. If you struggle with sleep, don’t hesitate to seek professional advice.

Resources

• Sleep Easy – book by Bernice Tuffery
• Australasian Sleep Association
• Beyond Blue – mental health and sleep
• Headspace – meditation and relaxation
• Cognitive Behavioural Therapy for Insomnia
• Sleep Health Foundation – Australia
• Healthify –  New Zealand
• Just a Thought – New Zealand