If there is anything that coffee is particularly known for, it's for being a powerful stimulant, helping in keeping us awake and perky.
Well, prepare to have your mind blown because a major study has found that having tea or coffee within 4 hours of your bedtime has no impact on sleep at all.
Researchers from Florida Atlantic University and Harvard Medical School monitored 785 people for a total of 5,164 days and nights, recording how much caffeine, alcohol and nicotine they consumed. These records of consumption were then compared with sleep diaries and wrist sensors that recorded the participants' sleep duration, sleep efficiency and how quickly they woke up after drifting off.
The study found that nicotine and alcohol did delay sleep but caffeine had no impact on sleep. Dr Christine Spadola, of Florida Atlantic University, wrote in the journal Sleep,
A night with use of nicotine and/or alcohol within four hours of bedtime demonstrated worse sleep continuity than a night without. We did not observe an association between ingestion of caffeine within four hours of bed with any of the sleep parameters.
The results of the study were 'surprising' to the team, but it was similar to previous evidence on the effects of caffeine on sleep. Nicotine was the one substance that appeared to have the worst impact on an individual's sleep pattern. On average, the data showed that nightly nicotine use was associated with an average 42.47-minute reduction in sleep duration.