Fastfood company McDonald's wants to boost US sales by encouraging franchisees to stay open all night.

The company slowed its new-store growth, favouring a growth a strategy of improved menus, decor, and operating hours, with once-sluggish sales vastly improving over the last two years.

About a fifth of the 13,700 U.S. restaurants now operate 24 hours, and that number could double in a few years. Restaurants can typically pick up an extra $300-$500 in daily sales by staying open, but some operators question the profitability due to higher insurance and equipment operating costs. The company may offer temporary rent rebates to franchisees that commit to operating all night long.