Blogs

By Evie Brandish. Edited by Dr Jo Bower.

The use of the term ‘sleep hygiene’ has increased dramatically over the past few years and refers to guidelines that gives everyone the best chance of a good night’s sleep. But what does ‘sleep hygiene’ actually mean, and what does it involve? In 2022, the NHS Foundation Trust published a leaflet detailing 11 ‘Sleep Hygiene Guidelines’ which should be achieved to sleep well. In this blog series, we will examine each of these guidelines in more detail to explain more about why they may help you improve your sleep. But before we delve into these 11 sleep hygiene guidelines, first, we will examine what sleep is and what happens when we sleep.

Sleep is a biological process which typically occurs every night. Sleep is driven by two biological processes which create the sleep-wake cycle. These are called our homeostatic process and our circadian rhythm (also known as our ‘body clock’). In most individuals without sleep difficulties, these processes help us to know when to go to sleep and when to wake up, with their influence constantly changing throughout the day and night.

So how do these processes work? The homeostatic process controls the drive to sleep. As we stay awake throughout the day, this homeostatic pressure to sleep builds up, until at the end of the day, we fall asleep. Conversely, once we are asleep, this homeostatic pressure dissipates, and the pressure to wake up builds across the night. Meanwhile, our circadian rhythm works to ensure that certain things (like sleeping) happen at the same time every day, through controlling the release of hormones such as melatonin and cortisol. These processes are critical for helping us fall asleep and wake up at similar times each day, and also for helping to determine the structure of our sleep.

When we sleep, we experience different stages of sleep which recur cyclically throughout the night. Sleep scientists measure these stages using special electrodes attached to the scalp, in a process known as polysomnography (PSG). Sleep can be categorised as either Rapid Eye Movement (REM) sleep or Non-REM (nREM) sleep, and nREM is split into three further stages.

The first stage of nREM sleep happens just as we fall asleep, and involves very light sleep where we switch between wakefulness and sleep and can be awoken easily. Sometimes people can also experience sudden movements in this stage and then a feeling of falling, which are caused by small muscle contractions.

NREM stage 2 involves less eye movements and can be detected by slower brainwaves when measured using sleep technology. In this stage there are unique brain waveforms known as K-complexes and Spindles, which are associated with aspects of our daytime functioning.

NREM stage 3 includes deep, slow waves and no eye or muscle activity and so is also known as slow wave sleep (SWS). This stage is important for restoration and repair (REF), and is also when some people may experience sleepwalking and nightmares.​

The last stage of sleep is Rapid Eye Movement (REM) sleep, this occurs every 90 minutes and involves deep breathing, frequent eye movements and paralysis of the body to avoid acting out our dreams or nightmares. We also experience an increased heart rate and blood pressure. REM sleep is important for our emotional processing and memory.

We all experience these sleep stages each night, however, everybody sleeps slightly differently. For example, the length of sleep that we experience, and the proportion of time spent in each sleep stage changes over our lifespan. Infants typically sleep for 14-17 hours with an equal proportion of REM and nREM sleep. However, as we grow older, our sleep time decreases. By the time we get to adulthood, healthy sleep duration is between 7-9 hours per night and approximately 75% of our sleep is nREM sleep.​

By Evie Brandish. Edited by Dr Jo Bower.

Sleep hygiene consists of multiple factors and is essential to maintaining good sleep quality and quantity. Although what constitutes good sleep hygiene can vary between different people, there are common factors which give us the best chance of achieving good sleep hygiene. The NHS Foundation suggests that these include:

1. Going to bed at the same time and getting up from bed at the same time every day 

2. Reduce or avoid sleeping during the day as naps longer than 30 minutes increase the likelihood of disturbed sleep at night 

3.Take regular exercise during the day but not 3 hours before going to bed

4. Avoid caffeine, alcohol and nicotine before bed

5. Avoid going to bed hungry or too full

6. Only use the bed for sleeping and sex

7. Don’t take your problems to bed-incorporate time earlier in the day to deal with issues that may cause you stress if they have not been dealt with

8. Try to have a relaxing bedtime routine-muscle relaxation, warm bath, milky drink before bed

9. Keep the bedroom quiet, dark and a comfortable temperature

10. Don’t force yourself to try to go to sleep-if it is taking you longer than 30 minutes to get to sleep, get up and do something peaceful until you feel sleepy​​ ​ ​ ​

11. Get regular exposure to natural light to help your sleep-wake cycle

Click on each recommendation in the blogs below, to find out more about sleep hygiene and the science behind it.

By Evie Brandish. Edited by Dr Jo Bower.

Having a consistent bed and wake time is a key component of this first sleep hygiene guideline…and yes…this includes weekends. If this guideline is only followed in the weekday and ignored at the weekends, this can create an inconsistency between our biological and social clock, which can feel similar to jetlag. In fact, this phenomenon is known as social jetlag!

By maintaining regular sleep and wake times throughout the week and weekend, we can avoid social jetlag and lots of the problems associated with it, which can include increased risk of developing diabetes and heart disease, and worsened mental health outcomes, including depression. 

One of the main reasons why it is so important to maintain a consistent bed and wake time is because it helps to ensure individuals are achieving the optimum amount of each sleep stage.

Non-Rapid Eye Movement (NREM) and Rapid Eye Movement (REM) are two different types of sleep which occur cyclically through the night and play different roles in our mental health and wellbeing. Researcher Dr Matthew Walker suggested that going to sleep later prevents us from getting the levels of nREM sleep that we need. Therefore, setting a specific and consistent time to go to bed (Dr Walker suggests between 8pm-12am)and to wake up each night will maximise our chances of getting the right amount of NREM and REM sleep each night. 

This sounds like quite a lot of pressure on us as sleepers to maintain a strict routine which we may struggle to consistently achieve. However, our neurobiology works to support us in this.

We all have two biological processes which create the sleep-wake cycle. In most individuals without sleep difficulties, these help us to know when to go to sleep and when to wake up. Together, our homeostatic and circadian processes constantly rise and fall throughout the day and night. Therefore, by introducing a consistent time to go to sleep and a wake up, your sleep routine is working with your natural sleep-wake cycle, which in turn helps make it easier to maintain a consistent routine.

This is perhaps one of the more difficult recommendations to follow. However, it is also helped by implementing some of the latter guidelines. Keep reading to find out more about these different sleep hygiene recommendations.

By Evie Brandish. Edited by Dr Jo Bower.

Napping has been integrated into many cultures for hundreds of years, but sleep scientists have only recently begun to investigate the science behind naps. Napping is very common, with up to 1/3 of Americans and almost 30% of UK middle-aged adults incorporating a nap into their daily life.

Often, people who nap suggest they do so due to general difficulties sleeping, particularly at night. However, more generally, the need for napping and the effects that it can have on an individual alters with age. For example, infants aged up to 1-year nap frequently, and this has been shown to improve their memory. Similarly, for teenagers aged 13-17 years, having a recovery nap can improve cognitive ability.

In adults, the benefits of naps are more unclear, and napping may even be associated with detrimental effects for some people. For example, regular napping in adults has been associated with increased rates of diabetes, depression, heart disease and Alzheimer’s disease. However other research has suggested including a nap into your day can minimise your chances of getting coronary heart disease.​ Therefore, the overall benefits and consequences of napping are likely complex and variable, depending on a range of factors.

Despite the overall debate regarding whether is beneficial to our health, there are some top tips scientists do agree on. So, for you to get the most out of your nap try considering following elements:

Timing: The best time to nap is in the early afternoon. This is aligned with our circadian rhythm, which has a ‘dip’ after lunch. Early afternoon naps will also have less of an effect on the homeostatic drive to sleep than those taken later, making it easier to fall asleep at bedtime.

Duration: Napping for 20- 30 minutes has been shown to increase our alertness. Sleeping for longer than this is not advised as it may have a greater impact on your ability to sleep at night. Longer naps can also lead to sleep inertia, in which individuals can experience disorientation and grogginess after waking up.

Caffeine: Consuming caffeine prior to a nap, may also be beneficial for increasing alertness upon awakening. Studies have shown that having caffeine 15-20 minutes before starting a nap can boost energy levels after sleeping. This may be because caffeine blocks adenosine receptors, which are part of our body's mechanism for promoting sleepiness. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Environment: As with your main sleep period, when choosing where to nap it is also important to pick a dark, quiet room with a cool temperature and a comfortable bed.​ This will give you best chance of sleeping, when you settle down to nap.

In conclusion, the need for a nap varies person to person. It is evident that although napping can have some benefits, it is important that naps are short, and appropriately timed. This means you can get the maximum benefits from your nap, whilst avoiding further disruption to your main sleep period. 

By Anna De Laet and Evie Brandish. Edited by Dr Jo Bower.

Sleep problems in infants with elevated likelihood of experiencing Autism Spectrum Disorder (ASD) may be explained by disruptions in sensory processing. In the first of our SINEA research blogs, PhD student and SINEA panel member, Anna De Laet, explains more.

In her most recent paper, Anna and her colleagues investigate sleep in infants at elevated likelihood of developing Autism Spectrum Disorder (ASD).

Although ASD is rarely diagnosed before the age of two, infants with a diagnosed older sibling are more likely to develop ASD themselves, with 20% receiving an ASD diagnosis at 3 years and another 30% exhibiting subclinical symptoms. This means that infants with an older sibling with ASD can be considered ‘at elevated likelihood’ of also having ASD.

Previously, parents of infants who were either at elevated likelihood or typical likelihood of ASD reported information on sleep disturbances when their child was aged 5, 10, and 14 months. When looking at this data, Anna found that infants at elevated likelihood of ASD took longer to fall asleep and woke up more often during then night than typical likelihood infants. This difference started to emerge from age 10 months, when infants with typical likelihood of ASD tended to improve in both sleep measures.

In order to understand why this difference might occur, next Anna and colleagues looked at whether there were differences in sensory information processing for elevated and typical likelihood infants.

In a previous paper with the same infants, the team applied pairs of vibrations to the infants’ feet, and measured brain activity in response to these vibrations. Typically developing infants experienced decreased brain activity in response to the second, identical vibration, as if they already know what is coming and do not pay as much attention to it. This process is known as sensory gating. However, the team found that for infants with elevated likelihood of ASD, brain activity in relation to the second vibration reduced less, suggesting that their sensory gating was diminished.

Anna’s final investigation was to examine whether the level of sensory gating is associated with sleep disturbances.

She found that infants who had reduced sensory gating (i.e. their brain activity remained higher in response to the foot vibrations) took longer to fall asleep, but did not wake up more frequently during the night. This is important information, as it can help identify potential causes of sleep difficulties as they are happening.

Evidence from this paper suggests that decreasing sensory stimulation for infants with elevated likelihood for ASD could help them to fall asleep more quickly.

For her next steps, Anna and her team remain interested in whether sensory gating can disrupt different aspects of infants’ sleep. At the moment, she is continuing the work by looking at how sounds disrupt infants’ sleep in infants at elevated likelihood for ASD and typically developing infants and whether reduced sensory gating plays a role in this. To find out more about Anna and the work in this blog, read the original paper or visit her website.