Did you ever wonder why you're more likely to doze off while lying in a hammock or sitting in a rocking chair? A small study from the University of Geneva in Switzerland suggests that the rocking motion allows some of us to go to sleep sooner than we do lying on a bed and encourages deeper sleep as well. The researchers asked 12 volunteers (none of whom had sleeping problems) to nap on a custom-made bed and on an experimental hammock. During their naps, the volunteers were hooked to an electroencephalogram (EEG) to monitor their brain activity. Results showed that all of the volunteers fell asleep in less time when lying in the hammock than when they were on the bed. The swaying motion of the hammock also boosted the duration of the sleep stage that normally occupies sleeping at night, and increased spurts of brain activity known as sleep spindles, which are consistent with deeper sleep. The researchers next want to study whether swaying or rocking can improve longer periods of sleep and help treat insomnia.