Sleeping Beauty
Science behind sleeping
The evolution of sleep is an ongoing subject of research. We do not know for sure why, but we do know that if an organism has more than an extremely rudimentary brain, it needs sleep to some extent, though exactly how it sleeps can vary. Some species can do "unihemispheric" sleep, where only one hemisphere of their brain sleeps at a time, allowing the other hemisphere to continue controlling the body.
The most widely accepted hypotheses for why sleep is needed both assume that the brain is doing some kind of maintenance task. One hypothesis is that the brain is cleaning out toxins, restoring resources, etc. It is when a lot of the brain turns off - if the neurons aren’t working hard they aren’t producing waste. Glial cells are like filters that make up the blood brain barrier. It’s the difference of a faucet flowing freely into a cup, or the faucet flowing into a Brita filter. The filter slows the flow of water. If you keep the flow in the faucet on, the reservoir in the filter will overfill and spill. But if you turn off the faucet the filter can catch up and empty the reservoir
The other hypothesis is that the brain is pruning away unnecessary or unused pathways, to help keep the whole system efficient and effective. A third hypothesis, unrelated to the brain, is that sleep is for conserving energy, but this is much less popular than the previous two, because sleep deprivation causes brain and behaviour problems in essentially all organisms that have a meaningful brain.
As for the consequences of sleep deprivation, they range from mild to extreme. Mild sleep deprivation usually causes irritability, fatigue, and reduced cognitive capacity, you may have experienced this if you pulled all nighters to submit university assignments. At moderate sleep deprivation, many become delirious or even experience hallucinations, and cognitive ability is severely impaired. Extreme sleep deprivation can cause coma or even death. In fact, you need sleep more than you need food, as most people can easily survive several days without eating (it's not fun but you can survive it), but a full week without sleep could possibly kill you.
And that's not even covering the consequences of long-term insufficient sleep. Even if you are getting sleep, but you aren't getting enough sleep, you'll have inflammation, your body won't heal its injuries as quickly, and you'll be almost constantly stuck in the symptoms of mild sleep deprivation, and everyone, myself included, have sacrificed their sleep for a loved one because we forget we are human too.
In short, sleep is important, but we don't really know why. Scientists' best guess is that we need it in order to keep our brains healthy, but the exact reason isn't known. Without it, you can feel awful, your mental abilities are impaired, and in an extreme case of sleep deprivation you could even die!
“Why We Sleep" by Matthew Walker, PhD is what my book club is currently reading and it is a fascinating look into sleep. So far I am learning from this book that sleep is absolutely more important than I'd ever realised just based on the incredible results of not getting enough sleep and/or not getting sleep at the right time.
Spirituality of Sleeping
1. Sleep can be spiritually significant
Sufi literature often treats sleep and dreams as connected to the inner/spiritual life.
The Qur'an itself describes sleep as a kind of temporary state in which the soul is taken, and Islamic tradition contains extensive discussion of dreams.
Sufi thinkers therefore sometimes saw dreams as potentially meaningful—but not every dream is considered a divine message.
2. Too much sleep can be associated with the nafs
Many Sufi teachings encourage moderation in eating, sleeping, and other physical pleasures.
The idea is not necessarily that sleep is bad. Rather, excessive sleep can become another form of attachment or indulgence that makes spiritual discipline more difficult.
A Sufi might therefore ask:
“Am I sleeping because my body genuinely needs rest, or because I am avoiding spiritual discipline?”
3. Night-time can be especially important
Sufi practice often places importance on waking during the night for prayer and remembrance of God.
This connects to the Islamic practice of tahajjud, voluntary night prayer.
The basic idea is that when the world is quiet and distractions are reduced, a person may find it easier to concentrate on God.
4. Sleep and spiritual “awakening”
There is also a metaphorical idea in Sufism:
Physical sleep → waking up physically
Spiritual “sleep” → waking up to God
Someone can therefore be physically awake but spiritually asleep—preoccupied with wealth, ego, status and worldly desires.
Spiritual practice is described as a kind of awakening.
Sleep is necessary for the body, but don't let sleep, comfort and worldly desires make the soul spiritually “asleep.”
Ibn Sina
Ibn Sina (Avicenna, c. 980–1037) discussed sleep mainly as a natural and necessary function of the body, especially in his medical work The Canon of Medicine. He wasn't a Sufi, although his ideas later influenced Islamic philosophy and medicine Ibn Sina believed the soul and the body mirror each other. When we say “I’m exhausted,” it’s often not work — it’s disorder. Irregular sleep, constant stimulation, zero silence.
A sick routine eventually convinces the mind that life itself is heavy. Maybe healing starts with structure, not motivation. Aristotle wrote On Sleep and Waking and asked why animals need sleep. He argued that sleep is closely connected with the functioning of sense perception. When we sleep, our sensory activity is suspended, but the underlying faculties remain present. Plato discusses sleep in The Republic, particularly in relation to desires. He suggests that when our rational control is weakened during sleep, hidden desires and impulses can appear in dreams. The basic idea is that dreams can reveal desires that a person normally keeps under control. This is quite interesting because it resembles a later psychological idea: that our unconscious desires can emerge when conscious control is reduced. Sleep could be understood as a reminder of human dependence on God, while spiritual awakening could mean becoming conscious of God and overcoming the nafs.
According to Plato, sleep is important partly because it reveals what happens to the different parts of the soul when rational control is weakened.
Plato's perspective
In The Republic (Book IX), Plato discusses what happens when a person is asleep.
When we're awake, our reason can control our desires and impulses. But during sleep, rational awareness is reduced. Plato says that desires that are normally controlled can become much more powerful in dreams.
For example, someone who is normally disciplined might dream about doing things they would never choose to do while awake.
Why does this matter?
Plato uses dreams to make a point about human nature:
Our rational self isn't the only part of us that contains desires.
The soul contains different elements, including:
Reason → seeks truth and wisdom
Spirit (thumos) → associated with courage, pride and honour
Appetite → desires things such as food, pleasure and possessions
When reason is not exercising control during sleep, the appetitive part can become more prominent.
So why is sleep important?
For Plato, sleep can reveal the condition of your soul.
If your desires are well-controlled, your dreams may be relatively orderly. If your appetites dominate your character, they can appear more strongly during dreams.
This connects to Plato's broader philosophy:
A good person is someone whose rational part governs their desires.
So sleep isn't simply "important because you need rest" in Plato's philosophical discussion. Dreaming gives Plato a way to investigate morality, self-control and the structure of the human soul.
Plato:
A person can be controlled by desires rather than reason.
Sufism:
A person can become controlled by the nafs and worldly attachment rather than awareness of God.
So both traditions are interested in the difference between living consciously and being controlled by lower desires, although their understanding of the soul and ultimate purpose is very different.
Al-Ghazali
For al-Ghazali, on the other hand believed that sleep was necessary for the body but should be kept in moderation. and its value depends partly on how it fits into ones spiritual life and sleep should restore the body without allowing attachment to comfort to produce heedlessness of God.
Al-Ghazali did not regard sleep as inherently bad. The body requires rest, and trying to eliminate sleep completely would be contrary to human nature.
However, he advocated moderation. Too much sleep can become associated with laziness and excessive attachment to bodily comfort.
Ghazali places considerable importance on how a person organizes their day and night around worship and remembrance of God.
Night-time can provide an opportunity for:
prayer
reflection
Qur'an recitation
dhikr (remembrance of God)
This is why voluntary night prayer (tahajjud) is significant in Islamic spirituality but also many religions have traditions of night-time prayer, meditation, or worship.
Why the night?
Praying at night is often understood as entering a different relationship with the self, the world, and the divine. Across traditions, night carries symbolic meanings that go beyond simply being a convenient time to pray. Specifically, the 90 minutes before sunrise is valued across traditions as a spiritually potent time for daily meditation and prayer The darkness becomes a metaphor for removing distractions and encountering what cannot be seen. During the day, the rational and social personality dominates. At night, dreams, intuitions, fears, memories, and desires become more prominent. Prayer then becomes less about obtaining information and more about surrender, trust, and direct relationship with the transcendent. At night, there are fewer voices, tasks, notifications, conversations, and demands competing for attention.
The prayer isn't necessarily "more powerful" because it is nighttime. Rather, the conditions make sustained attention and contemplation easier. Plato doesn't simply say "pray at night," but his philosophy gives an interesting framework for understanding why night time might matter. For Plato, the soul should be ordered by reason rather than appetite. During sleep, rational control is weakened, and the deeper desires can reveal themselves through dreams.
So one could interpret night time spiritual practice as an attempt to bring consciousness and order into the very territory where consciousness normally becomes less dominant.
This connects interestingly with Plato's discussion of dreams: when rational control relaxes during sleep, hidden desires can become visible.
The point isn't simply to sleep as little as possible. Rather, sleep should be balanced with spiritual practice.
Ghazali was interested in the fact that during sleep our normal awareness of the external world changes.
This raises a deeper question:
What is the relationship between the body, consciousness and the soul?
In Islamic thought, sleep can be understood as a state in which ordinary bodily awareness is reduced while the soul continues to have a different kind of existence.
This also connects to the Qur'anic idea that God takes souls at the time of death and during sleep, then returns those whose death has not been decreed.
Ghazali also discusses dreams and visions as part of his wider interest in different forms of knowledge. He does not treat every dream as a divine message. But he allows that some dreams can have significance, particularly for someone whose inner life has been spiritually cultivated. This fits his broader idea that purifying the heart changes how a person perceives reality.
Someone can be:
Physically awake but spiritually heedless or lack or care (ghafla)
or:
Physically asleep but whilst being spiritually close to God
So physical waking and spiritual awareness aren't exactly the same thing.
Conclusion
Sleep is important regardless of what a person believes about the soul. From a biological perspective, sleep allows the body and brain to recover and function properly. Philosophically and spiritually, sleep can also be understood as a period of restoration or renewal. Different traditions may interpret this differently for example, some religious thinkers understand sleep as a time when the soul enters a different state. Therefore, although people may disagree about what happens to the soul during sleep, the importance of sleep itself can be recognised independently of religious belief. On a philosophical level, the act of falling asleep requires an absolute stripping away of control. You cannot force sleep; you can only surrender to it. Goodnight!