Many people spend the Easter weekend relaxing and indulging in chocolate, but the Red Cross hopes a few thousand Australians will give up an hour of their time to donate blood.

Easter is a critical time for the Blood Service, because while many regular donors take a break, the need for blood does not stop.

And without donors coming in on Easter Sunday and Monday, hospitals could experience critical shortages.

"Unfortunately there are still patients in hospital who need blood, there are still cancer patients, and unfortunately there are often road traumas that happen over Easter," said Jess Willett, communications manager for the Blood Service.

"Often those people will have a lot of bleeding and it's really important that we have a lot of blood available to them if the worst does happen."

The demand for blood changes every day. ( ABC Radio Perth: Emma Wynne )

The supply of platelets — the clotting agent in blood — is of particular concern. They only last five days.

"If we didn't get donations throughout the long weekend, the platelets that we collect on Thursday will have been used or unusable by the time people come back to work on Tuesday," Ms Willett told ABC Radio Perth.

"Platelets are very important for cancer patients. It helps clot their blood."

Platelets are also used in emergency trauma situations.

'You get a good feeling'

One-third of Australians will need a blood transfusion or blood product at some point in their life, but only one in 30 regularly donate.

One of those regulars is Justin Mansillas, who made his 26th donation at the Perth collection centre this week.

"The initial idea of the needle going in probably isn't that nice, but for a small amount of inconvenience it's quite a big benefit," he said.

"I would definitely recommend it; you get a good feeling for not much inconvenience."

Mr Mansillas works long hours and finds coming to the donor centre a good way to take a timeout.

"It's actually a bit of a pause from a busy day, just sitting and relaxing," he said.

Nurse Jeannette Spark has seen what happens when supplies of blood run short in hospitals. ( ABC Radio Perth: Emma Wynne )

For nurse Jeannette Spark, giving blood offers an opportunity to have a rest and read a book.

She has also seen first-hand the importance of having a steady blood supply in hospitals.

"We use a lot of blood and a lot of blood products [in hospitals], plasma included.

"I have definitely been involved in situations where we have used all the resources we had available at the time.

"Donating blood is a great hour out of my day to relax, read a book and do some good."

The Red Cross now sends text messages to donors telling them where their donation has been used, an initiative both Ms Spark and Mr Mansillas support.

"It's very encouraging. It's nice to know that it has gone somewhere useful," she said.

2,000 donors needed

The Blood Service wants 2,000 people around Australia to make appointments to give this coming Sunday and Monday.

Bookings can be made by phone on 13 14 95 or online at donateblood.com.au.

"Donating blood is really easy," Ms Willett said.

The Red Cross is hoping to fill the donor couches at collection centres over Easter. ( ABC Radio Perth: Emma Wynne )

"Generally we say if you are aged between 18 and 70 and you are feeling healthy, there is a good chance you will be able to donate.

"The donation process only takes an hour of your time and the actual donation itself only takes about five to 10 minutes.

"Then you get a wonderful refreshment break afterwards with biscuits or chocolate or even some sausage rolls."