1. How sleep after learning enhances memory
Sleep after learning encourages brain cells to make connections with other brain cells, new research has shown for the first time.
The connections, called dendritic spines, enable the flow of information across the synapses.
One of the study’s authors, Dr. Wen-Biao Gan, said:
“We’ve known for a long time that sleep plays an important role in learning and memory. If you don’t sleep well you won’t learn well.
But what’s the underlying physical mechanism responsible for this phenomenon?
Here we’ve shown how sleep helps neurons form very specific connections on dendritic branches that may facilitate long-term memory.”
• The full article: how sleep enhances memory.
2. Why some people only need five hours’ sleep a night
While most people can get by with less than six hours sleep, the majority will suffer physically and psychologically, especially if sleep deprived over the long-term.
However, a gene mutation which means a person can function normally with only five hours’ sleep a night has been identified by a new study of 100 pairs of twins.
Those carrying the target gene variant slept, on average, for five hours, which was one hour shorter than their twins without the gene.
When the twins were given cognitive tests after sleep deprivation, those with the gene variant did better, making 40% fewer errors.
Not only that, but the carriers recovered more quickly from sleep deprivation, only requiring 8 hours recovery sleep, compared with their twins who needed 9.5 hours.
• The full article: Why Some People Only Need Five Hours’ Sleep a Night
3. You can learn a new language while you sleep
Being able to learn a new language while you sleep sounds too good to be true, but there may be some truth to it.
A recent study examined whether students learning Dutch could enhance their memory by listening again to new words during their sleep.
At 10 o’clock at night they were given a series of Dutch and German word-pairs to learn (they were native German speakers).
Half the group then went off to bed, while the other half had to stay up.
Both the sleeping group and those kept awake then listened to a playback of some of the word-pairs they’d learned earlier.
At 2am both groups were given a test.
Surprisingly, the people who’d been asleep did better on the words they’d heard while asleep than those who’d been awake.
The study suggests that listening to words during sleep can help us learn, likely because it activates the subject matter in the brain again.
• The full article: Learn a new language while you sleep
4. A strange cure for lack of sleep
Just believing that you’ve slept better than you really have is enough to boost cognitive performance the next day.
The findings comes from a study of 164 people who were given a lecture on how important sleep quality is and told they would be given a new test of how well they had slept the previous night.
After the test, some were told they’d slept well the previous night, others that they’d slept badly.
This had no relationship to how they had actually slept and were just made up to try and convince one group they’d slept better than the other.
Those told they’d slept better scored higher on tests of attention and memory than those told they’d slept poorly.
How you slept last night isn’t just about how you actually slept, it’s also about how you think you slept.
This study suggests that tweaking your mindset a little could be enough to boost your performance.
• The full article: A strange cure of lack of sleep
5. Eight hours sleep with interruptions as bad as only 4 hours
A full night’s sleep which is interrupted can be as bad as getting only half a night.
In a recent study, participants were awakened four times during a normal 8-hour night.
Each time they had to complete a computer task that took 10-15 minutes before they went back to bed.
In the morning they took tests of alertness, attention and mood. These were compared with results from two other nights when they’d had either:
- An uninterrupted 8 hours.
- An artificially restricted 4 hours.
The effects on mood, attention and alertness for the interrupted 8 hours were as drastic as only getting 4 hours sleep.
In comparison to the uninterrupted 8 hours, people felt more depressed, fatigued, confused and lower in vigour.
And this was the effect of just one interrupted night.
• The full article: The dangers of interrupted sleep
6. Teens need more sleep than adults
Failing to get enough sleep causes low mood in teenagers, along with worse health and poor learning.
But it’s not all down to late night video gaming or TV: the part of the brain which regulates the sleep-wake cycle — the Suprachiasmatic Nucleus — changes in puberty.
Teenage brains also secrete less melatonin so their ‘sleep drive’ reduces.
As a result, being forced to rise the next day at 6am for school or college means teens find it hard to get the 8 to 10 hours sleep that they need.
Although hormonal changes are partly to blame for teenage angst, being short of sleep significantly contributes to lack of motivation and poor mood.
• The full article: Teens need more sleep than adults
7. Poor sleep can lead to false memories
We all know that lack of sleep affects our memory, along with other cognitive abilities.
But now new research shows that not getting enough sleep increases the chances your mind will actually create false memories.
In the study, one group of participants were allowed to get a full nights’ sleep, while another had to stay up all night.
In the morning they were given a load of information about a crime — some true, some false — that had been committed.
The results showed that those who’d missed out on their sleep were the most likely to regurgitate the false information, rather than remembering the ‘true’ crime-scene photos they’d been shown moments beforehand.
The lack of sleep had messed with their heads to the extent that all the evidence — right and wrong — had got mixed up.
• The full article: Poor sleep can lead to false memories
8. The long-suspected danger of sleeping drugs
A new study has found evidence for a long-suspected danger of sleeping pills: an increased risk of death.
The large study looked at data from over 100,000 patients who had been to their family doctors across seven years.
It found that taking sleeping pills, like zolpidem/Ambien, doubled the risk of death.
Professor Scott Weich, who led the study, said:
“That’s not to say that they cannot be effective.
But particularly due to their addictive potential we need to make sure that we help patients to spend as little time on them as possible and that we consider other options, such as cognitive behavioural therapy, to help them to overcome anxiety or sleep problems.”
• The full article: Sleeping drugs increase risk of death
9. Sleep drunkenness disorder affects one in seven
As many as one in seven people may be affected by ‘sleep drunkenness disorder’ soon after they’ve woken up or during the morning.
Sleep drunkenness disorder involves severe confusion upon wakening — way more than just the usual morning grogginess — and/or inappropriate behaviour: things like answering the phone instead of turning off the alarm.
Confused awakenings can happen to people when very short of sleep or jet-lagged, but are regular occurrences for those with the disorder.
Researchers have found that 15% of people had experienced at least one episode of sleep drunkenness in the last year.
Of those, over half had one episode every week.
• The full article: Sleep drunkenness disorder
10. The daytime benefits of lucid dreaming
People who realise they are in a dream while they are dreaming — a lucid dream — have better problem-solving abilities, new research finds.
This may be because the ability to step outside a dream after noticing it doesn’t make sense reflects a higher level of insight.
Around 82% of people are thought to have experienced a lucid dream in their life, while the number experiencing a lucid dream at least once a month may be as high as 37%.
Dr Patrick Bourke, who led the study, said:
“It is believed that for dreamers to become lucid while asleep, they must see past the overwhelming reality of their dream state, and recognise that they are dreaming.
The same cognitive ability was found to be demonstrated while awake by a person’s ability to think in a different way when it comes to solving problems.”
• The full article: Daytime benefits of lucid dreaming
→ Try one of PsyBlog’s ebooks, all written by Dr Jeremy Dean: