Make a stock by bringing the chicken to a boil in a large saucepan with 3 litres of water, the onion and the celery. Cover the pan and simmer gently for 1 ½ hours. Allow to cool, skim off all fat before straining the stock and once cool enough to handle remove the chicken meat from the carcass and set aside.
Heat the olive oil in a large saucepan and add the carrot and leek. Saute for about 4 minutes then add the stock , chicken meat and rice. Bring to the boil then simmer covered for 45 minutes. Season to taste with sea salt and pepper.
Note: Chicken is also a good source of the sleep promoting tryptophan. Organic may be more expensive but it's an assurance the bird has not been fed hormones or antibiotics and has been raised under humane conditions.