Coffee's energy boost ALWAYS 'needs to be repaid with sleep' - Daily Mail

Dr Emma Beckett, a molecular nutritionist from the University of Newcastle, said this 'loan' of feeling awake will eventually need to be repaid with sleep.

This chemical is part of the system that regulates our sleep and wake cycle, with levels rising throughout the day as it is released as a by-product when energy is used by our cells.

Caffeine staves off drowsiness by temporarily blocking a chemical called adenosine, Dr Emma Beckett, a molecular nutritionist from the University of Newcastle, wrote on The Conversation website

'So eventually the caffeine breaks down, lets go of the receptors and all that adenosine that has been waiting and building up latches on and the drowsy feeling comes back – sometimes all at once.

Dr Beckett explained that while we are sleeping, adenosine levels drop as we are using less energy, meaning we wake up in the morning feeling refreshed.

The findings, published in the European Journal of Preventive Cardiology, applied to ground, instant and decaffeinated varieties, with researchers saying coffee consumption should be considered part of a healthy lifestyle.