Sam Fleishman suggests that the controlled use of sleeping pills helps to counter the life-disrupting consequences of insomnia (Nature 491, 527; 2012). But, to our knowledge, there is no convincing evidence that sleep medication can reactivate the health-restoring functions of sleep.

Good-quality sleep improves cognitive performance, vigilance, memory and mood. Poor sleep is associated with potentially damaging physiological effects such as inflammation (M. R. Irwin et al. Brain Behav. Immun. 24, 54–57; 2010), compromised immune-cell activity (E. Fondell et al. Brain Behav. Immun. 25, 1367–1375; 2011) and telomere shortening (A. A. Prather et al. J. Aging Res. 2011, 721390; 2011).

However, the regular use of sleeping pills has been linked with increased mortality and morbidity from infection, depression or cancer (see, for example, D. F. Kripke et al. BMJ Open 2, e000850; 2012).

Large randomizing trials are needed to evaluate the benefits and risks of sleeping pills so that they can be prescribed more responsibly.