Rocking is very beneficial for health at the physical and psychic levels. The rocking chair has even been used for therapy by President John F. Kennedy in the 1960s:

• The 'Kennedy Rocker' rocking chair (wikipedia)
• « The Kennedy Rocker »
  (http://www.thekennedyrocker.com/)
• History of Kennedy's rocking chair
  (http://www.thekennedyrocker.com/history.html)