Why you'll get your best sleep of the week tonight

The working week has only just started and you have 101 things to do. But take heart because you will sleep well tonight.

Analysis of heart rate data collected from almost 5,000 British men and women showed that while Tuesday night's sleep isn't the longest, it is the most restorative and refreshing.

It isn't clear why but it is possible that we feel we can relax after conquering the first two days of the working week.

And a Tuesday night's slumber is less likely to be disturbed by the effects of alcohol, rich food or other excesses more common later in the week.

The finding comes from an analysis of more than a billion readings collected by heart monitors worn by 4,866 men and women round the clock for three consecutive days during the past decade. In one of the biggest studies of its kind, volunteers also provided information on their sleep times and how stressed they felt.

As might be expected, men and women slept longest at the weekend, clocking up almost half an hour more in bed on Friday and Saturday nights than during the week.

However, this sleep was of lower quality, with substantially less time spent in "recovery state" than earlier in the week.

That type of sleep is particularly restorative and characterised by a drop in blood pressure and stress hormones and changes in how the heart beats.

While a stressed heart beats regularly, a relaxed one alternates between bursts of fast and slow. Just 48 per cent of Saturday's night and 48.7 per cent of Friday night's sleep revitalises the body and brain - compared to a healing high of 55.1 per cent on Tuesdays.

Monday nights are also restful, with 54.6 per cent of sleep deemed to be rejuvenating, according to the data from Finnish analytics company Firstbeat.

Boozy weekends are likely to be to blame for the end of week dip, the researchers said. Simon Shepard, of Optima-Life, the UK distributor for the 50p-sized heart monitors, said: "There is a big difference between rest and restoration.

"People rest for a lot longer during the weekend but perhaps they are out partying and letting their hair down and their bodies don't physiologically recover.

"On Mondays and Tuesdays, your energy levels may still be high after the weekend.

"And while you may still be sociable, you may be sociable in a different way, going to a book group rather than the pub."

The data also revealed that women sleep longer - but men sleep more soundly.

Typically, females in the study got 7 hours and 34 minutes of sleep each night - eleven minutes more than the men in their lives.

However, just 49 per cent of women's sleep is spent in recovery mode, compared to 54.5 per cent for men.

The women studied also said that they felt more stressed and were less likely to believe they got enough sleep. Mr Shepard said women's sleep may suffer from the strain of juggling working and family life.

Other possible reasons include women being more likely to sacrifice sleep for their other half and the monthly cycle of hormones disturbing women's rest.