Foggy, forgetful and running on four hours? How poor sleep affects memory and dementia risk in midlife, what the evidence says, and what to do about it.
You walk into the kitchen and can’t remember why. You lose a colleague’s name halfway through a sentence. You read the same paragraph three times. It’s easy to blame age, stress or one glass of red too many, but there’s a more boring suspect, and you can do something about it: you aren’t sleeping properly.
Sleep isn’t a luxury you’ll catch up on when you retire. It’s routine maintenance for your brain, and in your 40s, 50s and 60s that maintenance starts to matter more than it used to.
While you sleep, your brain is doing a lot of work. During deep sleep it sorts through the day and moves what’s worth keeping into longer-term memory. Cut that short and it’s like closing a document without saving it.
The effects of a bad night are familiar to anyone who has done a red-eye flight or a week with a newborn: slower reactions, a shorter fuse, poor concentration and a weakness for biscuits. Lose a little sleep night after night and those effects build up, and they become harder to notice because they start to feel normal.
NHS guidance says adults should aim for 7 to 9 hours a night. Plenty of men in midlife manage nowhere near that, and the hours they do get are often broken up by a full bladder, a snoring partner (or their own snoring) and a 3am worry about the mortgage.
This is the question that keeps people awake, which is ironic. The honest answer is that there’s a link, but it isn’t fully understood.
A long-running study of British civil servants found that people who regularly slept six hours or less in their 50s and 60s were more likely to be diagnosed with dementia later in life than those who slept around seven hours. That’s an association, not proof that short sleep causes dementia. Changes in the brain can begin years before symptoms, and disturbed sleep may be an early sign as well as a possible contributor.
There’s also a plausible explanation for how it might happen. Research, much of it in animals so far, suggests the brain clears out waste more efficiently during sleep, including the proteins linked to Alzheimer’s disease. Human studies point the same way, but the science is still developing. Be wary of anyone who sells it to you as settled.
You can’t control your genes, but you can control what time you go to bed tonight.
The practical point is the same either way. Good sleep helps your mood, memory, blood pressure and weight right now, and it may help your brain decades from now. That’s a decent deal for something that costs nothing.
If you sleep for eight hours and still wake up feeling as if you’ve been hit by a bus, think about obstructive sleep apnoea. The muscles in your throat relax during sleep and narrow or block your airway, so your breathing stops and starts, often many times an hour. Each time, you wake briefly to start breathing again, usually without knowing it.
NHS inform lists the signs as loud snoring, breathing pauses that someone else notices, gasping or snorting, and being very sleepy during the day. NHS England guidance adds poor memory, irritability and low mood. That sounds a lot like the brain fog many men put down to getting older.
Men, people who are overweight and people who drink in the evening are more at risk, because alcohol relaxes the throat muscles even further. The good news is that it’s very treatable, usually with a CPAP machine that gently pushes air through a mask while you sleep, or in milder cases a gum-shield-style device that holds your jaw forward. Treatment can also lower the risk of complications such as high blood pressure.
If your partner has started sleeping in the spare room or has recorded you on their phone, take the hint and book an appointment with your GP, who can refer you for a sleep study. If daytime sleepiness affects your driving, you may also have to tell the DVLA. Your GP can advise you on this.
Insomnia means regularly finding it hard to get to sleep, stay asleep, or waking far too early, and it becomes more common in midlife. Sleeping tablets can help some people in the short term, but they aren’t the recommended first treatment. Any decision about medicine is one to make with your GP or pharmacist.
The treatment with the strongest evidence is cognitive behavioural therapy for insomnia, known as CBT-I. It works by retraining the link between your bed and sleep, and by calming the racing thoughts that start the moment your head hits the pillow. It’s structured and practical, and it doesn’t involve lying on a couch talking about your childhood. NICE has recommended a digital CBT-I programme as an option in the NHS, and your GP can tell you what’s available locally. Access varies across England, Scotland, Wales and Northern Ireland.
Gadgets are a mixed bag. Sleep trackers can show you patterns, such as how much worse your sleep is after a late curry, but the readings are estimates, not medical measurements. If checking your sleep score every morning makes you anxious, take the watch off.
Basic sleep habits aren’t glamorous, but they work:
Get up at the same time every day, weekends included. A regular wake-up time does more than an early night.
Get daylight in the morning, ideally outside. It helps set your body clock.
Cut caffeine after lunchtime. It stays in your system for hours.
Don’t use alcohol to help you sleep. It might knock you out, but it breaks up the second half of the night and makes snoring worse.
Keep the bedroom cool, dark and quiet, and leave the phone outside it.
If you’ve been lying awake for what feels like 20 minutes, get up, do something dull in dim light and go back to bed when you feel sleepy.
Exercise during the day helps too, as long as it isn’t a hard workout just before bed.
If you’ve tried all this for a few weeks and you’re still struggling, or you’re worried about your memory, see your GP. Forgetfulness caused by tiredness is common and often fixable, but it’s worth getting checked.
Poor sleep affects concentration and memory in the short term, and regularly sleeping six hours or less in midlife has been linked to a higher risk of dementia later on, although the evidence shows an association rather than proof of cause. Aim for 7 to 9 hours, get up at the same time every day, and don’t rely on alcohol to help you sleep. If you snore loudly, stop breathing at night or still feel exhausted after a full night’s sleep, see your GP about sleep apnoea or about CBT-I for insomnia.
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