You should never sleep with a light on: TRUE
“We sleep better in the dark because light suppresses melatonin – the sleep-inducing hormone that regulates circadian rhythm,” says Dr Lindsay Browning, sleep expert at Trouble Sleeping and author of Navigating Sleeplessness. “Even with our eyes closed we sense light through our eyelids, so a dark room is preferable.” Consistency is also important, however, according to sleep coach James Wilson, AKA the Sleep Geek: “People who slept with a light on as children, or who grew up in a noisy house, may need a nightlight or white noise from the TV to feel emotionally secure enough for sleep.”
Teenagers need the most sleep: FALSE
“The recommendations are that teenagers aged 13 to 17 should get eight to 10 hours sleep a night, and 18- and 19-year-olds between seven and nine hours,” says Browning. “If teenagers sleep in at weekends or struggle to wake up for school, it’s not because they’re lazy or require more sleep, but that they go to bed later. During puberty, teenagers produce melatonin at a later time than younger children, so they have a biological inclination to go to bed and wake up later. They can also be more sensitive to light in the evening, delaying melatonin production.”
Children dream more than adults: UNCLEAR
“Babies and children spend more time than adults in REM sleep – the stage of sleep when most dreams happen – so it is likely that children dream more, but this has not yet been proved,” says Browning. “Adults may be better at dream recall than young children but it doesn’t necessarily mean they dream more. A child’s eye movement frequency during REM is not as high, suggesting their dreams may not be as intense.”
Never wake a sleepwalker: TRUE
“Although not dangerous, waking a sleepwalker would scare and confuse them, causing an adrenaline rush,” says Wilson. “Instead, talk and reassure them and put them back in bed. I work with lots of clients with parasomnia, from Premier League footballers who head the ball in their sleep to people getting up to make a sandwich.”
If you sleepwalk in deep sleep you are capable of carrying out complex tasks, such as driving a car, because parts of the brain controlling vision, movement and emotion appear to be awake, while areas involved in memory, decision making and rational thinking remain in deep sleep. In REM sleep, however, we are usually paralysed, although those who don’t experience muscle paralysis may act out dreams in a more harmful way, such as punching or kicking in their sleep.
Mitigate the risk of sleepwalking by knowing your triggers, which can include stress and anxiety, caffeine or alcohol before bed, high body temperature or a genetic predisposition.
You always speak the truth when you sleep-talk: FALSE
Sleep talking, or somniloquy, is most common during adolescence and may be caused by stress and mental health conditions, or stimulants such as coffee or alcohol before bed. “Around half of sleep talking tends to be unintelligible groans or mumbles but when someone is sleep talking understandable words, the most common word is ‘no’,” says Browning. “Just as dreams are not always true, people do not always speak the truth when they sleep talk.”
Sleep deprivation could kill you: TRUE
“You can go 19 days without food but only nine without sleep,” says Wilson. “Lack of sleep causes a build up of prion proteins in the thalamus [part of the brain that relays sensory and motor signals], which eventually causes so much damage to the brain and nervous system that sufferers die. But most of us need not worry as sleep is an instinct, like eating and drinking, so if you’re sleep deprived your body will automatically give you ‘microsleeps’, where you mentally zone out and drop into the stage of sleep just before you nod off.”
You sleep better at weekends: FALSE
“Anecdotally, people report sleeping better at weekends and on holiday because they feel more relaxed, but sleeping in isn’t always a good thing,” says Wilson. Consistent sleep patterns help regulate metabolism and a recent King’s College London study found that “social jet lag” from weekend lie-ins led to poor gut health and inflammation, plus an increased risk of heart disease and diabetes. Wilson adds: “There could be a psychological benefit to having a less busy mind at weekends, and sleeping in for 90 minutes won’t be an issue for most people. But long term, it’s better to go to sleep and wake up at the same time to stabilise circadian rhythm.”
Never sleep in your underwear: TRUE (ISH)
“For women, it is not advisable to sleep in tight underwear as it prevents airing of the sensitive vulval skin which can increase the risk of bacterial vaginosis or vulval candidiasis (thrush),” says Saurabh Phadnis, consultant gynaecologist and gynae-oncologist at London’s Nuffield Health St Bartholomew’s hospital. “It can also flare up or exacerbate skin conditions such as eczema, dermatitis and lichen planus and cause itching and discharge.”
However, Wilson suggests it’s worth considering hygiene: “The average person passes gas 15-20 times a day – including in your sleep – and research shows that a small amount of faecal matter comes out of the body at the same time. It’s a personal choice, but it may be more hygienic to keep underwear on.”
Men sleep better than women: TRUE
“Studies suggest that women need slightly more sleep than men and that women are one-and-a-half to two times more likely to report insomnia,” says Browning. “This is likely due to hormonal fluctuations during pregnancy, menstruation and menopause, higher rates of anxiety and depression in women compared with men, and women taking on more caring responsibilities,” says Browning. Wilson adds: “Light sleeping is a common problem for women in their 50s and 60s, which is often learned behaviour linked to years of waking with children.”
You swallow eight spiders a year in your sleep: FALSE
“Around a dozen spider species inhabit houses in Britain, but they are not attracted to the open mouth of a sleeping person,” says Geoff Oxford, honorary secretary of The British Arachnological Society. “This rumour was dreamed up in the early days of the internet to see how rapidly a fictitious ‘fact’ would spread. Surface-hunting (non-web-spinning) spiders rely on vibrations through surfaces or in the air to locate prey. A hot, damp, windy – possibly snoring – mouth is not conducive to this, nor is anywhere on a twitching, sleeping body. Likewise, web-spinners need stiff supports to anchor their webs, so they choose corners of rooms or crevices. Tiny money spiders on silk lines might accidentally be swallowed if people jog or cycle with their mouths open.”
Sleeping on your front aids digestion: FALSE
“Sleeping position doesn’t directly impact digestion because the processes are enzymatic,” says Rhiannon Lambert, nutritionist and author of Re-Nourish: A Simple Way to Eat Well. In fact, “sleeping on your front is discouraged due to the pressure it can exert on the stomach. When lying on your stomach, particularly after a meal, it can cause your stomach contents to press against the lower oesophageal sphincter, the muscular ring that separates the stomach from the oesophagus – increasing the likelihood of stomach acid flowing back into the oesophagus, causing acid reflux or heartburn.”
The bigger issue with front sleeping, according to Wilson, is back, neck and shoulder pain. “On your front, the neck is engaged and hands are usually above your head which causes discomfort after prolonged periods. Instead, adopt a foetal position on your side, using a body or knee pillow between your legs if necessary, and lay your head on a thicker pillow to keep your legs and hips neutral.”
The hours before midnight count for more than the hours after midnight: FALSE
“If you’re a lark, you might have more deep or REM sleep before midnight, but if you’re an owl that’s not the case,” says Wilson, who insists that getting up at 5am does not make you more successful and neither does going to bed at 9pm. “We sit on a sleep spectrum and your sleep type complements your surroundings and lifestyle. Plus how we sleep is up to 85% genetic. If you can sleep anywhere, then that’s inherited.” Browning adds: “People who go to bed before midnight tend to get more sleep than those who go after midnight simply because they get more sleep, as we all tend to wake at a similar time. Consistency and total length of sleep is more important than what time you go to bed.”
All beds have bed bugs: FALSE
“People confuse dust mites with bed bugs,” explains Wilson. Dust mites are microscopic and may trigger allergies and skin irritations if you’re susceptible, but they don’t bite, unlike bed bugs which are visible. “Bed bugs are caused by international travel and exist more commonly in clothes, luggage, on public transport and hotel beds than in homes. They spread easily, so minimise the risk of an infestation by using an encasement mattress protector and vacuuming your mattress regularly. Foam mattress are better than sprung at minimising space for bugs and mites to live in.”
Nobody sleeps through the night uninterrupted: TRUE
“Every night we wake up three to six times, but you need to be awake for five minutes to remember being awake,” says Wilson. “Humans are evolutionary predators, so nobody sleeps uninterrupted – our hearing is the last sense to switch off and the first to switch on when we sleep and wake. Moving at night is no bad thing and the number of movements we make fluctuates depending on factors like menstrual cycle and alcohol consumption.” Browning adds: “It is normal to move during sleep, from small twitches to occasional major body movements. However, sleep quality can be severely disrupted by a condition such as periodic limb movement (repetitive movements of legs, arms or both). If a child has five or more limb movements an hour, 15 for an adult, it could signal a sleep disorder.”
17 gallons of sweat are absorbed into a mattress every year: UNCLEAR
“We sweat during the night, but it is impossible to quantify the amount as this fluctuates depending on room temperature, body weight and gender – women can experience more night sweats during menopause or menstruation,” says Wilson. “You get hot sleepers and cold sleepers, so recognise your type and focus less on room temperature – which should be 16-18 degrees because a lower core temperature aids sleep – and more on allowing the body to breathe. The temperature between the duvet and mattress should be about 27 degrees. Hot sleepers should avoid memory foam mattresses because springs are more breathable, and go for light layers in natural fabrics that allow air flow, such as bamboo sheets or an alpaca fleece to wick away moisture. For cold sleepers, invest in merino wool pyjamas, and male and female partners should use separate duvets due to varying body temperature fluctuations.”
High earners sleep better than low earners: TRUE
On average, high earners (£75,000+) sleep for six hours and 25 minutes a night, which is over half an hour more than those earning the national average salary (£33,000), according to a recent Nuffield Health study. “Socioeconomic status is strongly associated with sleeping issues, with high earners and highly educated people tending to have longer sleep durations,” says Browning. “This is believed to be linked to higher levels of stress and financial insecurity, and longer working hours experienced by individuals from lower socioeconomic backgrounds. And shift workers tend to have significantly less sleep than nine to five hours because of the disturbance to circadian rhythm.”
• This article was amended on 19 February 2024 to add a 16th entry (“You should never sleep with a light on”), and to add the first names and job titles of James Wilson and Dr Lindsay Browning, which were accidentally deleted in the editing process.
