Why do we sleep?
Perhaps God knew we wouldn't truly rest without sleep.
Joseph had four dreams from the Lord. In the first, God told him to wed Mary. The second told him to leave at night for Egypt. In the last two dreams, God revealed to Joseph when to return and where to go. Scripture tells us many times that God can communicate with us in dreams, directly or in visions that need interpretation. Yet not all dreams are messages from God, just as only the widow at Zarephath in Sidon was Elijah’s hostess while there were many widows in Israel (Luke 4:25-26). Dreams are part of a typical night’s sleep for most if not all of us – even if we do not remember them. Dreaming is just one part of that most mysterious thing we do nightly: sleep.
The mysteries of sleep
Sleep, and its loss of consciousness, is not well understood. We know that sleep is complex in humans and animals, consisting of at least two different types with multiple levels. In REM sleep, the brain is as active as during the day. This is when we experience dreams. In REM, the brain is largely disconnected from the body, so we don’t carry out the movements of our dreams. Non-REM sleep has four distinct levels in which brain activity is very different from when we are awake. When we fall asleep, it is usually first into NREM and then into REM, and then we go in and out of the two types of sleep in 90-minute cycles.
Why sleep is necessary is not clear. We all know it cannot be avoided for long. In addition to the overwhelming desire to sleep, sleep deprivation leads to several adverse mental consequences like loss of concentration and a general decline in cognitive abilities. But going without sleep can also take a toll on our heart, pancreas and immune system. Preventing animals from sleeping can lead to their deaths. Yet exactly how sleep helps us is still being debated.
All God’s creatures sleep
There are at least two functions that sleep provides for our brains. First, sleep seems to help us consolidate memories of the day; we remember things better after a good night’s sleep. Testing this factor requires complex experiments because lack of sleep is stressful, but many different approaches have confirmed that sleep helps our memory system. In animal studies, researchers have seen the same pattern of neural activity in sleep as the animals experienced when moving through a maze, suggesting that replaying the neural activity in sleep helps strengthen the memory of the labyrinth – maze memory is better after sleep. Human studies have found that REM-sleep dreams can consist of fragments of events that have been important in the day, suggesting its role in memory. The second thing that happens in sleep, particularly in NREM, is that the brain gets rid of toxic molecules that build up during the day. There are suggestions that bad sleeping habits can accelerate the development of some dementias because brain toxins are not being cleared. Sleep may also have similar restorative functions for the whole body.
Even less understood are sleep problems. Experiencing a bad night’s sleep is unsettling and, for some, all-too-common. This is a critical topic probably needing another column.
God does not sleep (Ps 121:4), but it is clear he rests, giving us the Sabbath. Why we needed sleep in addition to rest on Sunday is not evident, but perhaps God knew we wouldn’t truly rest without sleep. It appears all of God’s creatures sleep, so this is not unique to us as image-bearers. Scripture speaks of a deep sleep in the creation of Eve, so it appears sleep occurred before the fall and is part of God’s good creation.
The Psalms speak of the gift of sleeping in peace because God cares for us. We all know how much better we feel after a good night’s sleep, so a wholesome sleep is a blessing from God, whether or not he speaks directly to us in our dreams.
This article first appeared in our January 10, 2022 issue under the title “To sleep, perchance to dream” If you like that title better, maybe you’d enjoy a print subscription! Check out your subscription options here.