This week: a gentle sound that seems to help the brain clean itself overnight, a huge study on why the type of sleep you get matters, a recycling milestone, a Pikachu on your wrist, and new sleep rules for nurseries.
Could a burst of pink noise help the brain clean itself while you sleep?
Researchers at MIT have shown that playing very short bursts of pink noise - a soft, low, rain-like sound - at precisely the right moment during deep sleep made the brain's slow waves bigger and, in turn, strengthened the waves of cerebrospinal fluid that rinse waste products out of the brain overnight. The team monitored 14 healthy volunteers with EEG and MRI at the same time and timed each burst to the peak of a slow wave. The sound was quiet enough that nobody woke up.
To be clear, this is a small lab study in healthy adults, not a product you can buy. The next step is to test whether stronger fluid flow actually improves memory or helps people with insomnia or early dementia. Still, it is a lovely reminder of how much repair work happens in deep sleep - our guide to why deep sleep matters more than you think has the background.
Why it matters: it adds weight to the idea that deep sleep is when the brain does its housekeeping, and that protecting it is worth the effort. Timed lab stimulation is a long way from steady pink noise through a DreamPod pillow speaker, so treat this as encouraging science rather than a hack.
It is not just how long you sleep, but what kind
A study of almost 96,000 UK Biobank participants, published in PLOS Medicine on Thursday, followed people for nearly nine years after they wore a wrist tracker for a week. Those whose trackers suggested more REM and deep sleep had lower rates of dozens of later conditions across heart, brain, metabolic and mental health, while sleeping under five hours a night was linked with the highest risks. Six to eight hours came out as the sweet spot.
The caveats are real, and independent experts were quick to raise them. Sleep stages were estimated from wrist movement by an algorithm rather than measured in a sleep lab, the study is observational so it cannot prove cause and effect, and undiagnosed illness may already have been disturbing people's sleep. One Cambridge expert noted that claiming six to eight hours "effectively reduces" disease risk goes beyond what this design can show.
Why it matters: the direction of travel is consistent with a lot of other research - regular, sufficient sleep is good for you - but do not panic over a wearable's REM percentage. If you are curious what the stages actually are, we explain them in the different stages of sleep, explained.
Dreams passes 1.3 million recycled mattresses
The bed retailer says its take-back scheme, where your old mattress is collected when the new one is delivered, has now processed more than 1.3 million mattresses since 2015, keeping over 42,000 tonnes of material out of landfill. The mattresses are stripped down by a specialist recycler so the steel, foam and polyester can be reused. Dreams timed the announcement for National Recycling Week and pointed to National Bed Federation figures suggesting only around a third of mattresses thrown away in 2023 were properly recycled.
Why it matters: a mattress is one of the hardest household items to dispose of well, and most people only replace one every eight to ten years. Whichever brand you buy from, it is worth asking whether they will take the old one away and what happens to it afterwards.
Google's Pokémon Sleep Fitbit starts shipping
A special edition of the screenless Fitbit Air began shipping on 15 September. It is the same lightweight sleep tracker Google launched earlier this year, in a soft blue band with a sleeping Pikachu print, and it feeds your overnight sleep and naps into the Pokémon Sleep game so that a good night's rest unlocks more Pokémon the next morning. It costs 129.99 dollars and, for now, is only on sale in the US and Japan.
Why it matters: gamifying sleep is a mixed blessing. For some people a playful nudge to get to bed on time is exactly what works; for others, chasing a score becomes one more thing to worry about at midnight. If a tracker makes you more anxious rather than more rested, that is a sign to take it off.
Nurseries in England now inspected on safer sleep
From 1 September, the updated Early Years Foundation Stage framework includes explicit safer sleep requirements for babies, developed with the Lullaby Trust, and Ofsted inspectors now gather evidence on every inspection that settings are putting them into practice. Ofsted has said breaches in this area can affect whether a setting's safeguarding is judged to have been met.
Why it matters: if you have a baby in nursery or with a childminder, you can reasonably expect them to explain how and where your child sleeps and what checks are done. It is a fair question to ask at your next drop-off.
That is the week. The common thread is a familiar one: the quiet, unglamorous stuff - enough hours, a regular pattern, plenty of deep sleep - keeps turning out to be what counts.
Sleep is a skill. We're here to help. SleepyDeepy.
