NELL Mattress Founder on Japan's 22-Trillion-Yen Sleep Debt Problem

Morght founder Koki Doi and sleep physician Yasuhito Nakatomi explain why Japanese sleep quality is among the world’s worst and how a pocket-coil mattress built from 300+ prototypes aims to fix it.

• Japan loses an estimated 22 trillion yen annually to sleep debt; Japanese rank among the world’s worst sleepers despite being the 4th-largest sleep market by spending.
• Doi founded Morght at 21 without attending university, after failing with 10 consecutive apps; NELL Mattress has now sold 220,000 units and earns over 200 million yen per day.
• NELL’s double-size mattress uses 1,734 pocket coils—roughly double the ~700 typical in luxury hotel mattresses—while pricing below comparable premium products by cutting distributors, compressing shipping, and selling direct.
• Doi prototyped 300+ coil variants, ultimately settling on wire diameters of 1.2mm and 1.3mm; the manufacturing machines themselves were custom-built to spec.
• Dr. Nakatomi identifies three root causes of poor sleep: insufficient duration, disrupted rhythm (including ‘social jet lag’ from weekend sleep-ins), and low sleep quality causing incomplete brain waste clearance.
• Poor sleep quality plus short duration raises mortality risk by 1.5x according to Japanese health ministry guideline data; only 54.5% of Japanese adults report adequate sleep time versus an 80% target.
• NELL offers a 120-day full-refund trial and a 10-year warranty with free replacement if the mattress degrades beyond spec—framing the purchase as a long-term investment rather than a product sale.

2026-04-27 · Watch on YouTube