For our end of season special, we have the rest of the NaPS lab in to answer a number of exciting sleep-related questions from our listeners. These touch on a range of different subjects from sleeps involvement in weight gain to alcohol's effect on sleep. Thanks to those who sent in questions!

List of Questions:

1. What is it in general anaesthetic that completely prevents a patient from waking up mid-surgery? Is this a similar state to being in a deep sleep or is this different entirely? 3:43

2. Can having daytime naps improve your memory? 5:24

3. Can a good sleep schedule help you lose weight? 6:40

4. Why do people tend to have a deeper sleep after drinking alcohol? 8:26

5. Can a lack of sleep really impact the way your brain works long term? 11:24

6. Why do children with ASD struggle to fall asleep and maintain sleep? 12:54

7. How does loud snoring or sleep talking wake up other people but not manage to wake up the person themselves? 16:13

8. How does drinking lots of caffeinated drinks affect our sleep wake cycle? 19:17

9. How does hibernation differ from a normal sleep in some animals? 21:05

10. When people say the term “just sleep on it” after a row or an emotional experience, is there any truth in this? Does sleep help you process emotions? 23:24

11. How much is sleep deprivation related to our immunity? 25:05


This episode was produced by Bella Mills-Smith

This recording is property of the sleep science podcast and not for resale

In this episode, we talk with Professor Chiara Cirelli from the department of Psychiatry at the University of Wisconsin.

We begin by hearing about how she first got interested in sleep research, and particularly about her time as a medical student at the University of Pisa where she worked on the noradrenergic system using cat models. We then look at the importance of using cross-species models in sleep research with flies, mice, rats and humans. We also discuss the different ways of using these animal models and the different advantages they offer for sleep research.

We then move on to Chiara's Synaptic Homeostasis Hypothesis. This hypothesis has been supported by data from a wide range of species, and suggests that an important function of sleep is to downscale synapses. During the day, brain connections (or synapses) relating to information we have learned get strengthened. This can result in a kind of neural saturation, whereby there is no space for more synapses. The Synaptic Homeostasis Hypothesis proposes that these synapses are downscaled during sleep, bringing about a form of homeostasis that allows us to repeatedly strengthen synapses during wake and downscale during sleep.

We also take a look at different ways of measuring synaptic growth across species such as molecular studies, structural or electrophysiological studies and the current difficulties in following synapses over long periods of time.

Finally, we look at Chiara's most recent finding which shows synapses associated with new learning are protected from downscaling during sleep. Instead, her latest data show that it is the background noise that is reduced during sleep, allowing for an increase in signal to noise ratio.

We hope you enjoy the episode and please find more information below.

Here are links to some of the studies mentioned in the podcast:

• Synaptic Homeostasis Hypothesis
• Synaptic Homeostasis Hypothesis in Memory Consolidation
• Downscaling

If you would like to find more information of Chiara's work, you can find a link to her research page here.

Glossary of terms
Synaptic Homeostasis - Renormalistion of overall synaptic strength to restore cellular homeostasis, preventing saturation and allowing further memory formation following a day of learning

ATP 'cost' - ATP is our source of energy for everything that we do. An ATP 'cost' would refer to how much cellular energy something would use.

Declarative learning - Learning about knowledge which we can talk about e.g dates, facts, events.

Drosophila - a genus of flies, commonly referred to as fruit flies, which are used regularly in scientific research.

Smart down selection - A process of selectively protecting synapses which need to be kept during downscaling.

Phosphorylation - Process of adding a phosphoryl group to a molecule. Phosphorylation can help regulate cell signals or protein development often acting as a way of 'labeling' cells.

Noradrenergic System - A neurotransmitter system within our nervous system that is often associated with alertness or arousal.

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Episode produced by Sophie Smith

Photo by Pixabay

This recording is property of the sleep science podcast and not for resale

In this episode, we interviewed Professor Reto Huber, who leads a research group at the University Children’s Hospital, Zurich. Reto’s interests encompass sleep disorders, development, synaptic plasticity and regeneration.

In this episode we discuss local sleep, a process whereby different parts of the brain express different depths of sleep or wake at different times. We consider the relationship of local sleep to phenomena such as sleep walking and sleep talking, and Reto explains a series of experiments exploring how local sleep relates to learning.

We then consider the use of drosophila as a model to study sleep and the sleep homeostasis hypothesis before switching topic to discuss the developing brain and sleep. Reto explains some important experiments linking sleep to plasticity. We discuss the differences in slow wave activity throughout development, and how the activity corresponds to experience dependent plasticity. We then consider a potential link to childhood conditions such as ADHD.

Finally, Reto explains closed loop auditory stimulation and some recent findings relating to local sleep and learning. We end the episode by exploring the potential use of the technique in clinical settings.

If you would like to read more on Reto's work, you can find a link to his publications here.

Glossary:

Local Sleep - A phenomenon in which different parts of the brain experience different depths of sleep or wake at different times.

Sleep Homeostasis- The optimal balancing of sleep and wake driven by sleep pressure and our circadian rhythms

Synaptic Homeostasis- Renormalising of overall synaptic strength to restore cellular homeostasis, prevent saturation and allow further memory formation following a day of learning

ADHD- Attention Deficit Hyperactivity Disorder

Closed Loop Auditory Stimulation- A method designed to enhance slow wave activity during sleep through auditory stimuli

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Episode produced by Vanessa Hyde & Sophie Smith

This recording is property of the sleep science podcast and not for resale

Photo by Ron Lach from Pexels

In this episode we talk to Professor Manuel Schabus and Professor Kerstin Hoedlmoser from the Centre for Cognitive Neuroscience at the University of Salzburg.

In this episode, we discuss their work on the development of sleep-in babies, first discussing what baby sleep is like and how it differs from older children and adults in regard to activity and sleep stages and specifically sleep spindles and why we think this is. We also look at the difficulties of recording sleep in babies and what other methods are used to analyse and assess baby sleep.

We then look in depth at the development on sleep spindles in babies and go on to discuss the difference between fast and slow spindles and their hypothesised importance in connection with memory consolidation and learning.

We also discuss the importance of coupling activity and synchrony in the brain, specifically sleep spindles and slow oscillations and how these synchronise as we grow and develop and why this synchrony is important for memory and cognitive function.


If you'd like to find out more about Manuel's work you can find a link to his research page here and a link to Kerstin's research page here.

Here are links to some of the studies mentioned in the podcast:

o Fast and slow spindles and their connection to cognitive and memory function
o Coupling of slow oscillations and sleep spindles and motor learning
o Coupling of slow oscillations and sleep spindles and memory

Glossary of terms

Sleep Spindle - These are a burst of neural activity which usually occur during stage 2 non-REM sleep.

(Synaptic) Pruning - The natural removal of extra synaptic connections between neurons which occurs between childhood and adulthood.

Declarative learning - A type of learning about knowledge which we can talk about e.g dates, facts, events. Episodic memory and semantic memory are types of declarative learning.

Alpha Activity - A pattern of electric actvity in the brain, alpha activity predominately occurs during rest with a frequency between 9-11Hz.


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Episode produced by Sophie Smith & Bianca Strete

This recording is property of the sleep science podcast and not for resale


Photo by Dominika Roseclay from Pexels

In this episode, we talk to Professor Wenbiao Gan from the Neuroscience and Physiology and Skirball Institute at New York University School of Medicine.

Professor Gan tells us about how he started to become interested in studying sleep and its impact on learning and memory.

He talks about intriguing and hands-on ways to assess the formation and elimination of dendritic spines in the mouse cortex, and how different experimental tasks like running backwards on a treadmill influence spine formation with or without sleep. Some counterintuitive results are presented and Professor Gan also shares his perspective on the synaptic homeostasis hypothesis.

In the end, Professor Gan gives some thoughts about the future of sleep research and suggests new methods of improvement in the area.

If you would like to find out more, here is a link to Professor Gan's full list of publications:

Links to the studies mentioned in the podcast:

• REM sleep promotes experience-dependent dendritic spine elimination in the mouse cortex
• Fear extinction reverses dendritic spine formation induced by fear conditioning in the mouse auditory cortex
• REM sleep selectively prunes and maintains new synapses in development and learning
• Experience‐dependent plasticity of dendritic spines of layer 2/3 pyramidal neurons in the mouse cortex
• Two-photon microscopy as a tool to investigate the therapeutic time window of methylprednisolone in a mouse spinal cord injury model
• Sleep contributes to dendritic spine formation and elimination in the developing mouse somatosensory cortex

Glossary of terms

• (synaptic) pruning = a natural phase in the development of the nervous system during which connections between neurons that are no longer needed die off
• dendrites = tree-like extensions of the neuron
• dendritic spines = extensions of a dendrite that help receive information from other neurons
• synaptic homeostasis = the idea that neural synapses cannot keep strengthening forever. Instead, they must also downscale at some point in order to make space for further strengthening. Such downscaling can be done in a relative manner that preserves information coded by the synapses in question.

Episode produced by Bianca Strete and Sophie Smith

In this episode, we interviewed Colin Espie, one of the world’s leading authorities on sleep and insomnia. Colin is Professor in Sleep Medicine at the University of Oxford, and Clinical Director of the Experimental & Clinical Sleep Medicine Programme, Sleep & Circadian Neurosciences Institute, again at the University of Oxford.

Professor Espie talks about sleep problems, explains why actively focusing on getting more sleep is not the best way to combat these issues. He also argues that behavioural approaches are much more effective even though clinicians tend to prescribe medicine by default. He has solid plans for changing the treatment of insomnia in the future and has already made a flying start eleven years ago by launching Sleepio, the online sleep clinic. Find out more about how Sleepio works and how can you register today by listening to this episode.

If you would like to have a look at the Sleepio website, you can do it by clicking here. You can also click here to find out more about Prof. Espie and read through recent publications mentioned in this podcast.

A new edition of Prof. Espie's book Overcoming Insomnia: A self-help guide using cognitive behavioural techniques, published by Little Brown Book Group will be released in late September.

This recording is property of the sleep science podcast and not for resale.

Glossary

· Hypermetabolised (brain) = having an elevated energy expenditure

· Hyperarousal = abnormal state of increased responsiveness to stimuli

· Chronotype = one’s natural inclination to sleep and be active at certain times of the day

· CBT (Cognitive Behavioural Therapy) = form of therapy aimed to improve mental health mainly through emotional regulation and developing coping mechanisms

· Sleep Restriction Therapy = a CBT therapy that works to decrease variability in the timing of sleep while increasing the depth of sleep

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Episode produced by Bianca Strete & Sophie Smith

In this episode, we talk to Professor Tore Nielsen from the University of Montreal and Professor Mark Blagrove from Swansea University.

In part 2 of this two part episode, we carry on our discussion about nightmares and talk about Tore's work on imagery rehearsal. A process where the dreamer rehearses their nightmares finding solutions to them in waking life in order to reduce stress and anxiety around nightmares and find more control in their dream life.

Then we move on to lucid dreaming and how this differs from imagery rehearsal. We take a look at Mark's work on how lucid dreamers have more control in their waking life and go on to discuss the possibly positive and negative effects lucid dreams may have on our REM dreams.

Finally, we discuss work from both guests on the dream-lag effect. This phenomenon, first discovered by Tore, occurs when life events are incorporated into dreams the night after the event and also 5-7 days after, but not in between. We discuss how the dream-lag effect was discovered and how it only appears to happen in REM dreams. We also discuss what this may means biologically and what impact it may have on memory consolidation.

We hope you enjoy this episode!

If you haven't already listened to it, part 1 of this episode is available on all podcast platforms.

If you would like to find out more about either Tore's or Mark's work, check out the links below. Tore's page here and Mark's page here .

Here are links to some of the studies mentioned in the podcast:

o Imagery Rehearsal
o Control in lucid dreamers
o Discovery of the dream-lag effect
o Replication of the dream-lag effect
o The dream lag-effect and significant personal events

Glossary of terms

Lucid Dreaming - This is a type of dreaming where the dreamer is aware they are dreaming. The dreamer in some cases can have control over the dream content.

Metacognition - Where one is aware of their own thinking and thoughts.

Idiopathic - A disease or condition which seems to have no known cause or appears spontaneously.

Dream-lag effect - A phenomena where life events are incorporated into dreams the night after the event and also 6-7 days after, but not in between.

****If you think we need to add a term or two here, please let us know****.

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Episode produced by Sophie Smith

In this episode, we talk to Dr Tristan Bekinschtein from the Cambridge Consciousness and Cognition Lab and discuss his research looking into the boundary between consciousness and unconsciousness.

We talk about his work in the loss of consciousness in vegetative state patients, sedation and sleep and his findings regarding brain markers which indicate when we change between these two states. We also discuss his research showing that people tend to neglect the left side of the world as they fall asleep and why this might be. We also talk about Tristan's other work in resilience and what makes our mind resilience to stressors such as poverty.

If you'd like to find out more about Tristan's work you can find a link to his research page here and a link to the Cambridge Consciousness and Cognition Lab page here.

Here are links to some of the studies mentioned in the podcast:

o P300 marker of consciousness
o Neglect of the left side of the world
o Animal or Object? Differentiation of semantic words whilst asleep

Glossary of terms from the podcast

P300 - Measured by electroencephalogram, this is a term for a spike response, occurring 300ms after an intended stimuli which is usually focused on by the participant.

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Episode produced by Sophie Smith