Coffee before bed actually doesn't keep you awake, according to new study

Good news for those that love a post-dinner cappuccino or even an espresso martini - a surprising new study has revealed that drinking tea or coffee within a few hours of bed won't actually impact sleep at all.

US researchers from Florida Atlantic University and Harvard Medical School monitored 785 people for over 5000 days, recording how much caffeine, alcohol and nicotine they consumed, and then comparing it against sleep diaries and wrist sensors.

The researchers found that caffeine had the lowest impact on the participants' sleep cycle, with almost no correlation between coffee consumption within four hours of bedtime, and sleep difficulties. 

Nicotine had a particularly harsh impact, with smoking resulting in more than 40-minute reduction in overall sleep.

Martin Reed, a certified clinical sleep health educator and founder of Insomnia Coach, told Healthline the results show a moderate amount of caffeine is the way to go. 

"As long as you don't drink pitchers and pitchers of coffee just before bed, caffeine is unlikely to have a major negative impact on sleep," he advised. 

However if you're smoking to relax, perhaps choose another method. 

"If we wake during the night and consume nicotine - perhaps in an attempt to help us relax - we can actually make it more difficult to fall back to sleep," he said. "I suggest trying to avoid smoking for at least two hours before you plan on going to bed and to avoid smoking if you wake during the night."

 Another study earlier this year also showed drinking coffee may help you lose weight.