Big Brother housemates are being forced to stay awake for up to 60 hours in the latest task on the reality TV show.
Jonathan said Gerry's talk of Greek history would send him to sleep
The contestants will collectively be allowed only four hours of sleep until Tuesday evening, facing basic rations if they fail to complete the challenge.
They have been provided with dressing gowns, slippers and hot chocolate in a bid to lull them to sleep.
This week's nominations will take place at 0200 BST, 24 hours after the sleep deprivation task began.
The housemates were informed they would have to stay awake on Sunday evening, after they had been awake for 11 hours.
They were given wine and cheese ahead of the announcement of the task.
Other sleep-inducing features have been introduced to the compound, including cushions and extra bedding, and large 'sleep' signs.
Contestants will be given a chance to earn extra hours on their collective Sleep Clock, by becoming sheep and jumping over fences in the garden.