To elucidate sleep disturbances in the etiology of peptic ulcers, the prevalence of peptic ulcer disease was compared among shift workers and daytime workers. The subjects (N = 11,657) were employees of various institutions, such as factories, banks, or schools, and had undergone a mass x-ray examination of the upper gastrointestinal tract. With present shift workers (N = 2269), the prevalence of gastric ulcers was 2.38% (N = 54) and that of duodenal ulcers, 1.37% (N = 31). With the past shift workers (N = 2111), the prevalence of gastric ulcers was 1.52% (N = 32) and that of duodenal ulcers, 0.62% (N = 13). On the contrary, with the daytime workers (N = 6525) the prevalence of gastric ulcer was 1.03% (N = 67) and that of duodenal ulcer, 0.69% (N = 45). The working schedule for 752 examinees was unknown. The prevalence of gastric and duodenal ulcers was higher with shift workers than daytime workers. Thus, shift work involving sleep disturbances may play an important role in the development of peptic ulcers.

Quantum yields of photoreactions of furylfulgides having Me, Et, n-Pr, or i-Pr on the furylalkylidene moiety were measured. The E–Z isomerization was greatly suppressed and the cyclization was accelerated when the alkyl group (R) became bulkier. When R was i-Pr, no E–Z isomerization was observed and the quantum yield of the colorizing cyclization was 0.62.

Two new thermally irreversible photochromic (R)-binaphthol-condensed indolylfulgides (with a 1-(1,2-dimethyl-3-indolyl)-2-methylpropylidene group and with a 1-(1,2-dimethyl-3-indolyl)butylidene group, 6 and 7, respectively) were synthesized. Because of rapid thermal equilibration between the conformational isomers of 7E at room temperature, photocyclization of a substantial portion of 7E occurred through (P)-7Eα to give (9aS)-7C selectively. On the other hand, as thermal equilibration requires a long time for 6E at room temperature, its photochromic interconversion occurs only between (P)-6Eα and (9aS)-6C, and the photocyclization-inert 6E remained unchanged. The thermal stability and fatigue resistivity toward the iterative photochromic interconversion of 7 have been proved to be excellent among the fulgide derivatives. The photochromic reactions were accompanied by large changes of specific rotation values. The X-ray crystallographic analysis of a visible-light-sensitive colored form, (9aS)-6C, was carried out.