Sleep is that little bit of magic that we all need to rest, rejuvenate and grow, so vital for our physical and mental health. Without it, we have trouble forming memories, concentrating on tasks, and reacting to stimuli.
Before we began studying sleep, scientists believed that the brain went into an inactive state when we slept. In time, however, the ability to record brain activity showed as the dynamic changes that take place in the brain when we rest. Today, we have a detailed idea about what goes on in our brain when we sleep, and what we really need it for.
Why and how do we fall asleep?
Several parts of the brain play a role in making you fall asleep. The hypothalamus—a peanut-sized structure on the underside of the brain—contains cells that promote and signal sleep. The brain stem controls the shift between the states of wakefulness and sleep, and also sends messages to muscles to stay relaxed when you are in deep sleep. The pineal gland produces melatonin, a hormone that helps you fall asleep after the lights go off.
While these parts help us fall asleep by relaxing muscles, movements and chemical activity, other centres get fired up in the process, helping us process emotions and also dream.
Stages of sleep
After falling asleep, our brain goes through different cycles of sleep, which we are able to identify by measuring eye movements and muscle activity. Our brains and bodies keep changing the way they behave in each of these cycles of sleep.
In all, there are 5 stages that can be classified into two phases.
Non-rapid eye movement (NREM) sleep:
The first part of the sleep cycle consists of NREM sleep. NREM sleep has four stages, with each stage lasting between 5 to 15 minutes.
- Stage 1 –During this stage, your eyes closed but you can still wake up with ease, and your eye movement begins to slow down.
- Stage 2 – We enter into light sleep. Your heart rate begins to slow down, your body experiences a drop in temperature, and your brain waves become slower. This stage can last anywhere between 10 to 15 minutes.
- Stage 3 – This is the stage of deep sleep. Your brain begins to produce very slow and languorous delta brain-waves, making it hard to wake up in this stage. If someone or something else wakes you up here, you will wake up very disoriented.
- Stage 4 – The healing stage. During this stage, tissue growth and repair of the body takes place. Important hormones are released, and cellular energy is restored.
Rapid eye movement (REM) sleep
This type of sleep takes place about 1-2 hours after you fall asleep. Brain activity actually increases during REM sleep, and rises to levels as high as when you’re awake because you’re dreaming.
Our body experiences several changes during REM sleep. We begin to breathe faster, have an increased heart rate, and our eyes begin to move particularly rapidly (hence the name). REM sleep is essential for us as it stimulates those areas of the brain associated with learning.
What is a good amount of sleep cycles?
Healthy adults need about 8 hours of sleep, during which we have about 4-6 sleep cycles – starting with NREM sleep, moving into REM sleep, and then drifting into NREM sleep again and so on and so forth. On average, light sleep constitutes 50-60 % of our sleep each night, and deep sleep constitutes about 10 to 25%. A failure to experience completed sleep cycles will make you wake up feeling disoriented, tired and even affect your memory and learning.
The best way to gauge whether you’re enjoying a healthy sleep-wake cycle is to check how you feel after you wake up and through the day. If you’re constantly fatigued, you’re probably not getting enough sleep or are having disturbed sleep.
Tips to enjoy a healthy sleep cycle
The first step is to avoid a few things that are detrimental to proper sleep:
- Although alcohol can make you feel tipsy and sleepy, it prevents you from having deep sleep and keeps you in the light-sleep stages.
- Avoid caffeine after sunset, because it prevents your brain activity from slowing down before bed.
- Avoid cigarettes because they contain nicotine, which like caffeine is a stimulant.
Practice the following habits instead to give yourself a night of deep sleep:
- Try to go to bed and wake up at around the same time every day. Your body likes consistency, and a regular schedule is an often overlooked key to good sleep.
- Try to get some physical exercise every day to tire yourself out and rid your body and mind of any extra energy.
- Make sure to get some sunlight during the day if you can. This will help your body regulate its natural circadian rhythm, ensuring that it knows when to begin triggering your sleep.
- Follow a bedtime routine. Turn off all your devices 1 hour before you sleep, avoid heavy meals at night, and practice meditation or light reading before sleeping.
- Make sure you have a comfortable mattress to lie on.
- Melatonin sleep supplements improve sleep quality. Try Setu’s non-habit-forming sleep supplements to restore and regulate your sleep cycles. If you’re taking any other medication, it would be a good idea to consult your doctor before you start taking any supplements.
1) Can sleep deprivation be associated with mental disorders?
Yes, mental illnesses and emotional upheavals can cause sleep deprivation. When the brain does not function properly and is working under stress, your sleep cycles get affected.
2) Do older people need less sleep?
Sleep requirements diminish with age, and older people may have trouble falling asleep faster, and also feel the need for less rest because of lower energy expenditure.
3) Why do I dream in my sleep?
Dreams help in reinforcing memory and brain activity. Researchers believe that we have several dreams each night, lasting between 5-20 minutes, but we forget 95% of our dreams after waking up.