It's a daily struggle known to office workers the world over: a productive morning rewarded with a decent lunch, and then, the leaden eyelids and urge to snatch 40 winks.
In Japan, where workers sleep less than in other countries, companies are encouraging employees to sleep on the job, convinced it leads to better performance.
Okuta, a home renovation firm near Tokyo, allows its employees to take a 20-minute power nap at their desks or in the staff lounge. Introduced two years ago, it has proved a huge hit.
"If I use a calculator when I'm sleepy, I have to double-check my work for fear of making mistakes, so it takes longer," Ikuko Yamada, who works in accounts, told the Yo miuri Shimbun newspaper. "I think my work performance has improved since I started taking naps."
Hugo Inc, an internet consulting company in Osaka, has a flexible approach: employees can take a 30-minute siesta any time between 1pm and 4pm.
Japan's workers have more reason than most to give in to the urge. According to a poll by the US National Sleep Foundation, Japanese workers sleep for six hours and 22 minutes on work nights - less than in any other country.
Only 54 per cent of Japanese respondents felt they slept well most nights. Only 8 per cent managed more than eight hours. British workers get only 27 minutes more, at six hours and 49 minutes, but Canadians, Mexicans and Germans all regularly achieve more than seven hours.
In Japan, inemuri - or "sleeping while present" - is considered the preserve of employees exhausted by their commitment to work, rather than a sign of indolence. Exponents of inemuri, however, have to remain upright to avoid appearing slovenly.
The sanctioned siesta has spawned an industry.
Workers in the Umeda business district of Osaka can visit a nearby public napping facility.
Tokyo's Ohirune Cafe Corne has eight beds for working women who want to sleep in partitioned comfort, soothed by the scent of essential oils. It charges 160 yen for every 10 minutes - and a pair of pyjamas for 100 yen.