Our alertness fades. We drift from being awake to asleep. Our heart rates and breathing both slow as the body begins to relax. When we enter the first stages of sleep, we enjoy a variety of restorative benefits: memory processing, emotional regulation, metabolic recalibration, and more.
This is light sleep - or non-REM (“NREM”) stages one and two.
Although jointly known as light sleep, the two component stages are radically different. Stage one is choppy and shallow. Think of it as twilight: the crossover point between wakefulness and sleep. Accounting for five per cent of our sleep, we pass through it swiftly and enter stage two.
Stage two is more defined and longer - accounting for more than half of our night. It’s the next layer of slowing. Our brain activity drops, blood pressure falls, and muscles relax. And it’s here that we enjoy a garden variety of restorative sleep benefits.
While light sleep is often maligned, discounted, and ignored, it is crucial to healthy sleep. Indeed, it contributes to a wide swath of physical, mental, and emotional functions. With its eclectic range of benefits, we can function on a handful of hours of light sleep - although we will be far from our best.
During light sleep, we see bursts of electrical activity in the brain called sleep spindles. They maintain the brain’s communication system and drive learning and memory processing. As the body rests, cell repair occurs - although not as energetically as in deep sleep.
[Light sleep] does some work on memory. It does work on body repair. It does work on hormones.
Param Dedhia, MD
Faced with apparent overrepresentation, many malign light sleep. They deploy biohacks to eliminate it and cultivate what they see as “better” sleep stages.
An overrepresentation in light sleep requires balance, not biohacking.
Light sleep isn’t a malignant effect to be cured or treated. In fact, it’s essential to restorative sleep.
Light sleep is our default stage. When we struggle to reach deep sleep and REM sleep stages, it expands to fill the gap.
An excess of light sleep is the smoke, not the fire. People focus on the light sleep, rather than why they aren’t getting deep sleep and dream sleep.
Param Dedhia, MD
When we sleep sufficiently long and still lack REM and deep sleep, it’s likely that something is suppressing later stages. We must increase our representation of deep and REM sleep, rebalancing our sleep stages.
But a glut of light sleep may not be the only challenge. It is possible to not get enough total light sleep, though this is typically a signal of not getting enough sleep overall.
The consequences of sleep deprivation are myriad and varied.
Without allowing our bodies to replenish our energy supplies, sleep deprivation leaves us feeling eternally exhausted. Depriving our minds of the opportunity to process conflict and negative thoughts renders our moods unstable and changeable. Our memories falter. Our immune systems malfunction. Risk of disease spikes and sex drive plummets.
Faced with low light sleep, prioritizing sleep duration is key.
We rarely - if ever - need to directly improve our light sleep.
It’s our default sleep stage. We slip into it easily and return to it often.
This fact has evolved into a dangerous sleep myth: that light sleep is broken and trivial.
Today’s sleep technology companies sell products to shrink and shorten light sleep. Influencers hawk biohacks to obsessively replace light sleep with REM and deep sleep - stages they claim are more valuable.
But the reality is that light sleep is also essential and irreplaceable.
Light sleep contributes to physical, mental, and emotional health. It’s an integrative sleep stage - it does a lot of little things. The nuance of light sleep is where the magic is.
Param Dedhia, MD
Accounting for more than half of our nights and contributing to a gamut of functions, light sleep is not a vestigial remnant or biological oversight. It is neither broken, nor underperforming.
Attempts to biohack light sleep are misguided at best - and folly at worst.