Jan. 9 (UPI) — Delta Airlines is pouring millions into revamping some of its older planes, adding extra seat space, updating lavatories and improving in-flight lighting.

The airline will spend $770 million through 2016 to make improvements to their A319s and A320s and their 25- to 30-year-old 757-200s.

The A319s and A320s will get new, wider seats in coach, increasing rear-room from 17.2 inches to 18 inches. And while that might sound like an inconsequential amount, research conducted by the London Sleep Centre found that quality of sleep improves by 53 percent when seat width is increased from 17 to 18 inches.

Unfortunately, Delta is also making the new seats slimmer, so they can cram more passengers on each plane. The A319s and A320s will also get new overhead bins with larger capacity to boost carry-on space by 60 percent.

Delta will also update the LED lighting in cabins and giving the on-board lavatories a spruceup.

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