The one mistake you make before bed that keeps you up for HOURS, according to scientists

Late-night caffeine and midnight feasts are known to disrupt our sleep — but experts are warning that something else is driving restless nights.

Posting on social media shortly before bed can delay the time it takes for people to fall asleep by up to three hours, according to a study by Duke University.

The researchers of 50,000 people found those who posted on social media within an hour of their bedtime were nearly twice as likely to stay up late.

Those who posted several times shortly before bed were also more likely to still be awake late into the night than those who posted just once.

It is thought that getting likes and comments causes an adrenaline rush that blocks sleep hormones. Blue light exposure from our phones is also known to disrupt the sleep cycle. 

Dr William Meyerson, a data scientist who led the research told The Sun: ‘This could be the result of several factors — from screen lights disrupting the circadian rhythm to the anticipation of a response,’ he said.

‘Reddit users are more likely to stay up past their bedtime and post on nights when they posted an hour before bedtime, especially if they were active on high-engagement forums.’

For the study, published this month in the journal Sleep Medicine, researchers looked at data from 51,000 people who used Reddit.

They looked at 236million posts put up by users between 2005 — when the platform was created — and 2021.

Scientists used a model to estimate users’ bedtimes based on the time stamps of their Reddit posts.

They then analyzed data from when users posted within an hour of their average bedtime compared to nights when they posted much earlier to find out whether their bedtime was delayed.

Results showed that on nights when users first posted early in the evening, only about six percent were still posting after their estimated bedtime.

Data also showed that when users put up one post late in the evening, 10 percent were still posting after their bedtime.

But when they put up four or more posts late in the evening, 23 percent were still posting after when they normally fall asleep.

The researchers wrote in the study: ‘We observed that users were much more likely to remain on Reddit one to three hours after their respective estimated average bedtimes on nights when their last pre-bedtime Reddit posts were within one hour of their estimated average bedtime.’

Researchers have long warned that using screens late at night can keep someone up because it disrupts the circadian rhythm — or the body’s sleep-wake cycle.

At night when the sun goes down, levels of melatonin — the sleep hormone — begin to rise in the brain, causing us to feel sleepy.

But being exposed to blue light from screens can suppress the hormone’s release.

Posting on social media late at night could also disrupt sleep because they can be left with a feeling of anticipation.

Many will wait to receive notifications in response to their post, with each triggering a release of dopamine — the feel-good hormone — in the brain.

This boosts mental activity and alertness, making it difficult to relax and delaying the wind down needed before sleep.

Limitations of the study included that it relied on estimated average bedtimes, rather than reports from users.

It also could not account for people who were passively consuming social media, or viewing and reading posts without commenting.