Millions of Brits heading abroad this summer could lose the first two days of their holiday to a 'holiday sleep hangover', a sleep expert has warned, with the effects of disrupted travel lingering long after they return home.

New research found that over three quarters of Brits (76 per cent) admitted travelling affects their sleep – while more than two in five admit tiredness affects at least the first day of their holiday.

Data analysed by sleep technology firm Simba shows nearly 18 per cent of Brits have already booked or are planning to book a trip abroad this summer, meaning more than 23 million adults could experience holiday-related fatigue.

Lisa Artis, Deputy CEO of Simba's charity partner, The Sleep Charity, says the so-called 'holiday sleep hangover' is caused by a combination of early airport starts, disrupted routines, poor sleep while travelling, unfamiliar hotel rooms and jet lag.

'The holiday sleep hangover has become the hidden physical and mental cost of modern travel. Sleep disruption usually starts much earlier and can continue long after you've unpacked your suitcase,' she said.