Plenty of us wake up each day feeling like we could do with a little more sleep.

In fact, at least one-third of the adult population regularly suffers from significant sleep problems.

Thirty-five per cent of Australians don't feel refreshed when they wake in the morning and the same proportion wakes frequently during the night.

Recent research suggests we should forget about counting how many hours sleep we're getting - and instead start thinking about sleep according to the cycles it works in.

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The brain has a pattern of sleep. You don't just fall asleep and hour one is the same as hours two and three and five and nine. It goes through cycles.

As such, the Sleep Calculator could be just what you need to get a better night's sleep.

The tool flies in the face of the old theory that getting an early night in is the best way wake up feeling rested.

Instead, it aims to help users nod off on to the start of a new sleep cycle so you wake up at the end of one - and as a result you avoid feeling groggy when you wake.

The creators of the tool, blind retailer Web Blinds, explain "getting a good night's sleep is about more than simply going to bed early - it's about waking up at the right time too.

"Using a formula based on the body's natural rhythms, the Sleep Calculator will work out the best time for you to rise or go to sleep."

The calculator counts back from the time a person needs to wake in 90 minute cycles and takes into account a '15 minute dropping off period'.

So, if you need to be at the office by 9am, rising at 8am, it advises that you either go to bed at 10:46pm or wait for the next cycle to begin at 12:16am.

In January website Hillarys.co.uk launched the Lost Sleep Calculator that reveals your sleep loss over the course of a week, month, year or even your lifetime.

The website also exposes how long each person tosses and turns in bed thinking about things distracting things like food, work and sex.

Visitors to the Lost Sleep Calculator have to input their age and the amount of sleep they had the night before.

The tool then works out if the individual has slept enough or not and calculates how much sleep they are losing over the course of a longer time frame, like a month or year.

Using data from a survey of more than 2500 adults, Hillarys.co.uk worked out how long a user spends restless in bed because of other thoughts.

The poll discovered that most of us are kept up at night with thoughts of things like arguments with friends and family or sex with our partners.

The site also reported a correlation between lack of sleep and increased bad moods and feelings of loneliness.

When people are starved of sleep they also struggle to concentrate. This translates to an economic toll, with a 2011 report by Deloitte Access Economics finding sleep disorders cost Australia more than $5.1 billion a year in healthcare and indirect costs.