Schools in Brighton and Hove are giving pupils bottles of water to help end the mid-afternoon malaise and boost their chances of academic success.

It is common for people to feel tired and out of sorts after the morning's efforts and a lunchtime refuel, But it is not just adults who suffer, as Cathy Moore, headteacher of St Andrew's Primary School, knows.

For years she noticed pupils becoming tired and lethargic after lunch and children visiting the sick room often suffered from head and stomach aches.

This has all changed since a water bottle policy was introduced at the Monmouth Street school.

Mrs Moore said: "We have found it really good.

"The children have reported back positively and so have the staff who have been doing the scheme as well.

"The pupils are a lot less tired, in particular after lunch, which was always a bit of a dip.

"Quite a few who had reported problems with headaches and stomach aches have found they are not getting them anymore."

St Andrew's was told about the scheme by Hilary Reed, a learning support service teacher for schools in Brighton and Hove.

Mrs Reed said: "I realised a lot of the children I was teaching were very dehydrated. They were suffering from headaches, stomach aches, temper tantrums and were feeling very tired.

"I did some research and found the brain shrinks when it is dehydrated. So I decided to draw up a school water bottle policy.

"I started by writing letters to all the primary schools and did talks in some of them.

"St Andrew's was the first to implement it. Now about two thirds have taken it up. I am starting to introduce it at secondary schools, of which Hove Park is the first."

Through her research, Mrs Reed discovered the brain was 75 per cent water and children needed to drink at least 1.75l a day for their brains to achieve the highest potential.

One fifth of children drank no water at all and some had even lost the thirst reflex.

Mrs Reed said: "This is a humanitarian issue. Children should be allowed to drink water. Without it they work day after day with the same feeling adults have if they go into work with a hangover."

Under the scheme, children bring 500ml clear sports bottles to school. Some participating schools have been sponsored and bottles have been provided for them.

Examples of this are St Andrew's and Hove Park, which were both given 500 bottles by Sainsbury's. West Hove Primary School was given some by Buxton.

Mrs Moore explains how the scheme at St Andrews works. She said: "The bottles have to be clear so we can make sure the children are drinking water and not juice or fizzy drinks.

"Bottle tops are better because they mean the water cannot be spilled on equipment.

"The bottles are kept in the classroom during the school day and can be refilled as and when at drinking water taps throughout the day.

"They are taken home each evening and it is the responsibility of parents or guardians to wash them.

"To start with, the children went to the toilet a lot more frequently but once they become hydrated, after about ten days, this slowed down and now we usually find they can normally manage just going at playtimes and lunchtimes.

"Science shows if you are dehydrated you make more trips to the toilet than if you are not because your body is trying to give you reminders to drink more.

"At first it was a novelty but as time has gone it has turned into a routine that works. It encourages children to drink water, which is beneficial for their health.

"If they see their friends, around them drinking it then they drink it too.

"When we started it I had a lot of parents say to me their children did not like water but we have found that all children drink water. The scheme has created a way to make children want water."

Mrs Reed is hoping Hove Park will, in time, set the precedent for all secondary schools in the city to take part.

Hove Park headteacher Tim Barclay said: "There is a recommended intake of water for children and adults which is often not the amount people drink. So we are trying to introduce a water policy.

"It should help those pupils who are not being able to perform to their highest level because they are dehydrated.

"We are hoping it will raise their achievement and improve their health."