Can a smell wake you up?
It's much nicer to wake up to coffee in the morning than a waft of ammonia after fainting.
Asked by: Keith Stephenson, Walsall
Smelling salts (ammonium carbonate) have been used since at least the 17th century to revive a patient from a faint. They work because the ammonia gas irritates the lungs and triggers an inhalation reflex, which alters the breathing patterns and elevates blood oxygen levels.
With ordinary sleep, it is quite possible to be woken by the smell of coffee or frying bacon, which stimulates the appetite and raises arousal levels.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.
May Half Price Sale
- Save up to 52% when you subscribe to BBC Science Focus Magazine.
- Risk - free offer! Cancel at any time when you subscribe via Direct Debit.
- FREE UK delivery.
- Stay up to date with the latest developments in the worlds of science and technology.