Go to bed at one's usual time.
Gently drift off into the Land of Nod accompanied, as always, by the dulcet tones of Radio 4.
Suddenly get yanked back to the Land of Wide Awake and feel one's blood pressure shoot through the roof as a yell of pain assaults the eardrums.
"What happened? Are you OK?"
"Yes!" (hissed through gritted teeth.) "I caught my foot on the bathroom door."
Feel the pain as he hobbles into the bedroom...
Now thoroughly awake, lie there tossing and turning for the next two hours while the cause of one's wakefulness slips instantly into deep and peaceful slumber.