It is well known that during sleep newly learned information is
transferred from short-term to long-term memory stores in humans. In the
study that is now being published in the scientific journal SLEEP,
sleep researchers Jonathan Cedernaes and Christian Benedict, sought to
investigate the role of nocturnal sleep duration for this memory
transfer, and how long-term memories formed by sleep remain accessible
after acute cognitive stress.
Following a learning session in the
evening during which 15 participants learned 15 card pair locations on a
computer screen, in one experimental session subjects slept for half a
night (4-hr) and in the other for a full night (8-hr). The next morning
subjects were asked to recall as many card pair locations as possible.
What the researchers found was that half a night of sleep (4-hr) was as
powerful as a full night of sleep (8-hr) to form long-term memories for
the learned card pair locations.
However, the study also revealed
that stress had an impact on the participants’ ability to recall these
memories. The men were acutely stressed for 30 minutes in the morning
after a half or full night of sleep (for example by having to recall a
newly learnt list of words while exposed to noise). Following short
sleep this stress exposure reduced their ability to recall these card
pair locations by around 10 percent.
In contrast, no such stress-induced impairment was seen when the same men were allowed to sleep for a full night.
“On the basis of our study findings, we have two important take home
messages: First, even though losing half a night of sleep may not
impair memory functions under baseline conditions, the addition of acute
cognitive stress may be enough to lead to significant impairments,
which can possibly be detrimental in real-world scenarios. Second,
interventions such as delaying school start times and greater use of
flexible work schedules, that increase available snooze time for those
who are on habitual short sleep, may improve their academic and
occupational performance by ensuring optimal access to memories under
stressful conditions”, says Jonathan Cedernaes, researcher at the
Department of Neuroscience, Uppsala University.
next step will be to investigate how chronic sleep loss and or more
chronic stress may interact to impair the ability to retrieve memories
that are consolidated during sleep”, says Jonathan Cedernaes.
The sleep-deprived brain can mistake friends for foes
Time to get more zzZzzs.
A new UC Berkeley study shows that lack of sufficient sleep hinders our ability to accurately read facial expressions.
the experiment, subjects could not distinguish between threatening and
friendly faces after being awake for 24 hours. As a consequence, study
participants interpreted more faces, even the friendly or neutral ones,
as threatening when they were sleep-deprived.
“Consider the implications for students pulling all-nighters,
emergency-room medical staff, military fighters in war zones and police
officers on graveyard shifts,” said study lead
author Andrea Goldstein-Piekarski.
“Insufficient sleep removes the
rose tint to our emotional world, causing an overestimation of threat…”
said co-author Matthew Walker.
عن حذيفة بن اليمان رضي الله عنه قال: “كان النبيُّ صلَّى اللهُ عليهِ وسلَّمَ إذا أخذ مضجعَه من الليلِ، وضع يدَه تحت خدِّه، ثم يقول : ( اللهم باسمك أموتُ وأحيا ) . وإذا استيقظَ قال : ( الحمدُ لله الذي أحيانا بعد ما أماتنا وإليه النشورُ ) .” صحيح البخاري
Narrated Hudhaifa: When the Prophet (ﷺ) went to bed at night, he would put his hand under his cheek and then say, “Allahumma bismika amutu wa ahya,” and when he got up, he would say, “Al-Hamdu lil-lahi al-ladhi ahyana ba'da ma amatana, wa ilaihi an-nushur.” Sahih al-Bukhari 6314 In-book reference : Book 80, Hadith 11 USC-MSA web (English) reference : Vol. 8, Book 75, Hadith 326