The REM Reality Check
Adults are guilty of four habits on average which experts warn could be sabotaging REM sleep - the phase crucial for memory, emotional processing, mental performance and brain development.
A new study of 2000 UK adults, commissioned by sleep technology firm Simba, analysed the behaviours most commonly linked to reduced REM - one of the most restorative stages of sleep, finding that a shocking 86% of people were guilty of one REM blocking habit.
REM, or rapid eye movement sleep, is the fourth phase of slumber when the brain does its most important overnight work.
“REM is when dreams occur, but its role goes far beyond dreaming.” says Lisa Artis, deputy CEO of Simba’s charity partner The Sleep Charity, “It’s when the brain processes emotions, consolidates memories and clears away mental “waste” from the day, leaving you sharper, more resilient and ready for the day ahead.”
“Think of REM as your brain’s overnight reset button. Without enough of it, you can sleep for hours and still wake up feeling foggy, emotionally off-balance or overwhelmed.”
The four most common REM killer habits were all everyday behaviours. More than half of adults admitted to using their phone before bed (52.5%), while a similar proportion said they regularly drink caffeinated drinks after 3pm (51.6%), despite caffeine staying active in the body for hours.
Stress-related habits were also widespread, with over a third of respondents saying they lie awake thinking about work pressures (36.7%) or financial worries (36.9%), both of which can prevent the brain from fully entering REM sleep.
Artis believes maintaining healthy REM is key to emotional wellbeing, learning, and cognitive performance.
Regular sleep problems affect millions of adults, with 41% reporting difficulty falling asleep and more than half (51%) waking during the night.
Despite the NHS recommending a minimum of seven hours, the average Brit is sleeping just 6h 04 min a night, according to Simba’s research - with women getting around 11 minutes less per day than men. [Men average: 6h10m vs 5h 58 women]
Past studies show people with restricted sleep get significantly less REM than those who sleep normally.
As REM periods become longer and more frequent in the later part of the night, cutting sleep short disproportionately reduces this important stage.
Previous research also links sleep loss to impaired brain processes normally handled during REM, like memory consolidation, helping explain why skimping on sleep can leave you foggy, forgetful and more emotionally stressed.
But Artis warns it’s not just about how long you sleep. “Even people getting eight hours can still miss out on REM if their evenings are filled with stimulation, stress or habits that keep the brain in alert mode.”
The vast majority [81%] of those hitting NHS sleep guidelines still reported habits that can disrupt REM, reducing the brain’s chance to recover properly overnight.
Simba’s study asked participants about their evening routines and bedroom environments in a typical week. The most common habits linked to REM disruption included:
Simba’s REM Gap Index, reveals the habits and pressures robbing us of this vital stage of rest.
REM Killer |
% of adults admitting habit in an average week³ |
Why it matters for REM |
|---|---|---|
|
Blue-light exposure within 30 min of bed |
52% |
May delay melatonin, which pushes back the body clock and makes it harder to enter REM on time. |
|
Late-night doomscrolling / digital overload |
50% |
Keeps the brain in “alert” mode, making it harder to relax into REM and more likely to wake during it. |
|
Caffeine after 3 p.m - coffee, energy drinks, |
52% |
Blocks the chemical (adenosine) that helps you feel sleepy, reducing the depth and continuity of sleep needed to reach normal REM cycles. |
|
Alcohol within 2 hrs of bed |
25% |
Suppresses REM in the first half of the night and causes lighter, broken REM later on. |
|
Bedroom temperature >22°C |
24% |
The body struggles to cool down, and overheating is known to reduce both the amount and stability of REM sleep. |
|
Partner movement / shared bed disturbance |
33% |
Causes micro-awakenings that interrupt REM cycles, which need continuous, undisturbed sleep to complete. |
|
Work stress and financial anxiety |
37% (each) |
Raises stress hormones like cortisol, which make it harder for the brain to transition into and maintain REM. |
|
Smoke, vape or use nicotine products before bed |
28% |
Acts as a stimulant, making sleep lighter and reducing the time spent in REM. |
On average, adults admitted to four REM blocking habits/killers, putting their restorative sleep at risk.
How to Tell If Your REM Sleep Is Being Affected
Artis explains that without sleep trackers or lab tests there are still warning signs you may be missing out on this restorative stage of sleep.
Nearly half of British adults say they rarely remember their dreams (45%) or wake feeling sluggish and unrested (47%), while around two in five struggle more with irritability (39%) and find everyday stresses harder to handle (42%) - all indicators linked with disrupted REM.
“Even people clocking eight hours in bed may still be missing key REM cycles if their routines include multiple REM stealers,” says Lisa Artis, Deputy CEO of the Sleep Charity.
Among those who reported all 11 habits, 96% said they rarely remember their dreams, compared with just 36% of those who reported only one REM-disrupting habit. This suggests a clear link between evening behaviour and perceived sleep quality.
“Even if you’re spending eight hours in bed, habits like late-night screens, caffeine, or alcohol can reduce the restorative quality of your sleep,” says Lisa Artis “ Simba’s REM Gap Index shows how common these behaviours are and why protecting REM is so important.
“Not protecting your REM sleep can leave you forgetful, moody, and less able to cope with everyday stress. Even losing a little each night can build up, leaving you drained and emotionally worn out.”
Lisa Artis’ Tips to Protect REM Sleep
1) Stop screens at least 30 minutes before bed
Blue light exposure in the evening may delay melatonin, the hormone that helps signal night-time sleepiness. This can delay your internal clock and make it harder to enter deeper sleep stages.
2) Cut caffeine after 3pm
Caffeine makes it harder for your body to feel ready for sleep and can reduce how deeply you sleep. When it’s consumed in larger amounts or too close to bedtime, it can also interfere with REM sleep, the stage that plays a big role in how rested and refreshed you feel the next day.
3) Keep your bedroom at 16–18°C
The body’s core temperature naturally drops for sleep; a cooler ambient room environment supports that thermoregulatory process and more stable, uninterrupted sleep.
4) Avoid alcohol within 2 hours of bed
Studies show that consuming alcohol before bed decreases total REM sleep and disrupts the normal progression of sleep stages.
5) Reduce partner movement and overheating
REM sleep depends on long, uninterrupted sleep cycles. Even small movements from a bed partner - rolling over, getting in or out of bed - can trigger micro-awakenings that break these cycles before they’re complete.
Simba’s Hybrid Mattress is designed specifically to limit this disruption. Its individually responsive spring system moves independently rather than as one connected unit, meaning movement on one side of the bed is far less likely to travel across to the other. This is paired with pressure-relieving foam layers that absorb impact and dampen motion at the source.
Survey Methodology:
The research was conducted by Censuswide, among a sample of 2,000 Nat Rep Consumers. The data was collected between 17.12.2025 - 22.12.2025. Censuswide abides by and employs members of the Market Research Society and follows the MRS code of conduct and ESOMAR principles. Censuswide is also a member of the British Polling Council.
