Britons waste 30 million hours a day "sleep-working", according to a new study, which showed the nation's workforce is not firing on full cylinders until 9.56am.
Despite the average Brit physically getting up at 6.57am, the study shows people are not mentally alert until almost three hours later.
Consequently, more than 30 million productive working hours per day – or seven billion per year – are lost through "sleep-working".
And though almost 70 per cent of respondents said the morning is their most important time of day, it is also the time they are least productive.
Two thirds admit they may be found sleep-working for most of the morning, with one in ten saying they do not feel 100 per cent mentally alert until early afternoon.
In the workplace, police are the most mentally alert profession with 78 per cent stating they are fully alert by 9.30am, followed by 68 per cent of those working in telecoms and 67 per cent of those in finance.
Bottom of the list are those in construction - 65 per cent not alert – and those working in retail – 56 per cent.
The study, conducted by Tickbox for Quaker Oats, last month, questioned over 1,200 people.
A spokesman for Quaker Oats said: "A large amount of Brits find they are not able to mentally wake up until almost lunchtime.
"The solution to this problem is simple – breakfast will kickstart your day and ensure you get the most out it."
The study was undertaken to mark the launch of the world's first Porridgemade – a Teasmade-type device, designed to have a fresh bowl of porridge ready by the bedside each morning.