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'Get the best zzzzs': How deep sleep clears your brain's toxins

Gayatri Vinayak
·10-min read
Circadian rhythm as educational natural cycle for healthy sleep and routine. Labeled biological clock rules explanation with day scheme for wellness vector illustration. Inner physical body schedule.
Circadian rhythm as educational natural cycle for healthy sleep and routine. Labeled biological clock rules explanation with day scheme for wellness vector illustration. Inner physical body schedule.

A new study led by Dr Ravi Allada from Northwestern University, Illinois, has revealed the vital role deep sleep plays in removing toxins from the brain. Studies have shown that deep sleep can help clear waste that remains in the brain in the form of toxic protein build-up, thereby helping prevent neurodegenerative diseases.

Dr Allada and his team of researchers found that fruit flies who are in the proboscis extension sleep (PES), which is similar to the human deep sleep stage, repeatedly extend and contract their snout. This, according to the study, helps facilitate the movement of waste out of the body. This movement was affected when the team disturbed their sleep.

The benefits of a good night’s sleep can’t be emphasised enough. Numerous studies have linked inadequate sleep with diseases and problems such as obesity, diabetes, cardiac diseases. Quality sleep, on the other hand, has been found to help improve concentration and productivity, uplift the mood and slow down the ageing process.

However, it can also be one of the most elusive things, especially for people suffering from sleep disorders. So how do you enhance the quality of sleep you get?

We speak to Nithra Institute of Sleep Sciences’ Dr Nileena NKM, MD in Psychiatry and Fellowship in Sleep Medicine, on the benefits of deep sleep and how we can better the quality of our sleep:

How can deep sleep clean up the brain?

Our body goes through four sleep cycles as we progress into deep sleep – three stages of n-REM (non-Rapid Eye Movement) and a REM (Rapid Eye Movement) stage. There are different brain activities and brain waves associated with each stage.

When we conduct sleep studies, we pick up these different brain waves and brain activities. These brain waves, in turn, help in modulating the flow of cerebrospinal fluids, the clear fluid in which our brain is suspended.

These fluids act like a solution cushioning the brain and spine, providing nutrition to the brain and removing toxins. Studies show that the cerebrospinal fluid pulsates during deep sleep, flushing out toxins from the brain, which are picked up by our blood vessels and expelled from our body through our kidneys.

Researchers are also studying the impact of deep sleep on Alzheimer’s disease. Sleep plays a vital role in clearing beta-amyloid which are toxic amino acids that can influence Alzheimer’s. Deep sleep can help prevent Alzheimer’s to some extent or atleast delay the progression into it.

What are some of the biggest mistakes we make that affects deep sleep?

Something that I often notice among people, especially the older generation, is that they go to bed way too early and then wait for sleep to set in. However, this may not always work. If you go to bed when you are not sleepy, you tend to toss and turn. If you are waiting for sleep to set in, you could end up developing sleep anxiety. This is counterproductive.

Secondly, the length. Staying in bed for more hours than what your sleep requirement does not help. You end up getting segmented sleep and waking up feeling tired. This can take a toll on your mental and physical health.

Since each stage has its own function when it comes to hormonal balance, cognitive function, memory, concentration, mood swings, etc, quality, rather than quantity of sleep, is very important. Too much sleep can be as bad as sleep deprivation.

Some believe that sleeping 6-8 hours is a waste of time. What are your thoughts on this?

We frequently see that in urban setups, our lives are compromised. Long commutes take a toll on our physical health and mental health. We also have so many roles to fill in with work and family lives, that we compromise on sleep.

Adolescents are often the most sleep-deprived people. This is a concern as our brain comes into full development and goes through fine-tuning, during these years. If you do not get good sleep, it can affect your academics and take a toll on your future mental health.

Sleep is necessary; however, the point is also whether you require these 6-8 hours of sleep. Most people are obsessed with the number of hours. Sometimes, you require only 6 hours. So, taking medication and trying to extend into 8 hours, is also bad for health.

Listen to your body and decide what minimum amount of sleep you require. If you feel good after 7 hours of sleep and it allows you to function at 100 per cent the next day, then that is what you require.

The pandemic, and accompanying worries, has intensified sleep disorders for many.

Yes, we have a lot of people with new sleep disorders coming to us. We are also seeing people whose sleep problems were cured earlier, returning.

The main issue during the pandemic is the disruption of routine in terms of waking up, going out for work, eating, with people staying at and working from home. People are also not getting as much physical activity as when they were going out to work.

The lack of sunlight is another concern. Sunlight gives us Vitamin D, but it also plays a great role in tuning our biological clock. When our brain gets good morning sunlight, it will tune it to sleep earlier.

How can we overcome this?

The mantra is simple – early sunlight, early sleep; late sunlight, late sleep. Try to go for a morning walk, within your safety zone by following all the safety protocols. If not, ensure you are sitting in a sunlit area in your house.

At home, we expose ourselves to all forms of artificial bright lights. It is equally important to dim your lights in the late evening so that the mind realises that it is night and time to sleep.

Many people ask if they can use a blue light filter. Earlier studies supported this theory, but we have also learnt that there is a specific wavelength of blue that needs to be used. Hence, try to avoid all gadgets.

Sleep is elusive with little kids. How do we get them to go to bed early?

It may be difficult to control the time that children go to sleep. But you can control what time they wake up. We suggest slowly advancing the time that the child wakes up in the morning. This could then get them tired earlier, and in bed, earlier as well.

Some children may also face difficulties sleeping when their mothers are not around. You can work around this in a gradual manner. For example, lie down with your child in bed for some time. Then, stay in the same room, but move to a chair near the bed until the child falls asleep. You can then slowly increase the distance between the bed and the chair.

Once your child is comfortable, move out for some time, reassuring your child that you will come back in five minutes. Return within five minutes the first time, but slowly increase the gap. Your child may have slept off by the time you are back.

Tips to follow to ensure sleep hygiene:

Here are Dr Nileena’s tips to help bring on deep sleep:

Keep a fixed sleep schedule. If you sleep at 12 am one day and at 10 pm the next, wake up at 8 am one day and 9 am the next, your body gets confused. This is especially so during the weekends when we tend to compensate for the weekdays.

Don’t cover a bad night’s sleep by sleeping in during the day. This takes a toll on the sleep the following night. Rather, try to wake up at the usual time so that you break the vicious cycle and sleep properly in the night.

Bedroom quality: The bedroom itself should have a relaxed atmosphere. While it may be difficult in an urban setup where accommodation is limited, try to keep the clutter out of the bedroom. Go for a soothing colour palette, rather than bright and loud colours. Maintain a comfortable temperature – neither too cold nor too warm. It is also important to keep lighting to the minimum.

Noise is another factor, especially in urban setups where there is a lot of street noise. Try to see if you can reduce the noise, sometimes even a fan helps to dampen the noise. You can also try a white noise machine.

Stick to power naps: Sleeping during the day time is ok, but not for more than 15-20 minutes. If you go beyond that, you enter deeper stages of sleep and end up feeling groggy.

Further, don’t take more than one power nap a day. My patients often tell me that they take a half an hour nap in the morning and a half an hour in the evening. This extends the number of hours of sleep during the day.

Avoid caffeinated beverages and alcohol: Try to minimise caffeinated beverages such as coffee and cold drinks, especially in the evening. For some people, the effect of caffeine can last upto ten hours. Read labels carefully to check for caffeine. Have warm non-caffeinated beverages in the evening, instead.

Limiting alcohol is also extremely important, not just for sleep, but to address a wide array of health concerns.

Resist the urge to check the time while sleeping: This could cause anxiety as you start calculating the number of hours you have slept.

Avoid working right before sleeping: Often when people are working on their laptops, they close it and go off to sleep immediately. Here, the mind is not getting time to relax and unwind. You should go to bed feeling relaxed and ready to sleep.

A bed is for sleeping: We tend to eat in bed, work on the bed, play games or watch TV while sitting on the bed, scroll through our social media feed in bed. However, our own default setting with regards to the bed is that it is a place to sleep. By multitasking on the bed, we dilute that conditioning. Keep the bed exclusively for sleep.

Take a warm bath: Avoid hot or cold bath as this could affect your sleep. A lukewarm water bath, on the other hand, could help promote sleep.

Write your to-do list down: Rather than thinking about what you need to do the next day, note them down on a piece of paper and tick off what has been done. You, thus, put a symbolic stop to the thought process.

Early dinner: Try have dinner atleast 2 hours before bedtime. When you go to bed feeling full, you can get acidity and heartburn. This will hamper sleep. Also, avoid very spicy food.

You can drink a glass of warm milk with honey or have a banana as they help increase serotonin levels, which is a natural mood enhancer.

Interestingly, night time milk, which is taken from cows during the night, is known to enhance sleep. This could be because it has more melatonin concentration in it at that point in time.

Cherries and kiwis are also known to help promote sleep.

Light exercises: Light physical activity such as stretching exercises in the evening, help. However, rigorous exercise during the evening or night should be avoided. This is because when we do strenuous exercises, our body may get tired, but our mind gets excited. So, keep rigorous for the day time, at least 4-6 hours before bedtime.

Other relaxation techniques: You can try progressive muscle relaxation. Here, you tense each part of your body and then slowly release the tension and relax the muscle group. Self-hypnosis, though there is not much clear research in on, has also been found to help some people. Relaxation techniques such as yoga, Tai Chi and mindfulness need training.

Reading is also a relaxing activity but stick to light reading and not mysteries and thrillers. Also, avoid reading on the bed. Sit on a comfortable chair next to the bed and then progress to your bed when you feel sleepy.

You can also try guided imagery. This helps calm the mind and rein in racing thoughts. Through guided imagery, you are guiding your mind into imagining something.

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