Matthew 25:5

‘Now while the bridegroom tarried, they all fell asleep and slept for some time.'

But there was a delay in the Bridegroom's coming, just as there had been delay in the return of the Master (Matthew 24:48). Thus Jesus' teaching concerning His coming has built into it the idea of unexpected delay. He wants all to know that it will not necessarily come as soon as expected. And the result was that inevitably all fell asleep, and then continued to slumber or drowsed off and then went to sleep. There was nothing sinful in that. We all have to sleep. Indeed as long as they were ready it was a wise move. The folly lay in not making full preparations before going to sleep. Note the aorist followed by the imperfect. They fell asleep and went on sleeping. Or alternately ‘they became drowsy and then went to sleep'.