Why 8 Hours Sleep May Feel Like 4 to a New Parent

So, you went to bed at 22:00 p.m. last night and woke up at 6 a.m. That is 8 hours—the definition of a good night’s sleep. Then what gives? Why are you still feeling so exhausted? Disrupted sleep is to blame.

If you have a baby, it is not uncommon for their squawks and feeds to awaken you every couple of hours. The trouble with that is your brain gets stuck in light sleep, never quite getting the chance to descend into deep renewing sleep. This causes a degenerative problem of new parent sleep deprivation because, unfortunately, your baby’s normal sleep cycles are not yours.

To get technical on sleep disruption, REM sleep—when we dream—makes up about 15% of our slumber. And NREM—the sleep that revives and renews us for the new day ahead—is about 85% of sleep.

The deepest segment of NREM sleep, Stage 3, is considered the sleep sweet spot. Basically, you are sleeping like a log. Breathing is slow and regular, and your face and body are relaxed but not floppy. It is called ‘slow wave’ sleep because your brain waves switch from jittering little bounces seen during awakening to slow undulating waves. These waves wash over the brain 1000 times a night, erasing memories from the day just passed and preparing your brain for a new day of learning.

In this deepest sleep, you are tough to rouse—and when you do awaken, you need a minute or two to figure out where you are. However, you can still awaken for important signals, like a smoke alarm or your baby's cry.

The Mismatch That Leads to Disrupted Sleep

One pivotal difference between adults and babies is that adult sleep cycles last 90 minutes while babies keep cycling up and down in just 60.

Babies’ quicker cycles mean they return to very light—easily disturbed sleep—every hour. And when disturbed, they may grunt, groan…or awaken fully to eat! Those disturbances often fracture our sleep cycles—right in the middle—and chip away at your NREM.

When robbed of NREM sleep, our body and brain have not been adequately restored and refreshed. New parents often feel like they are in a state of insomnia—we awaken feeling tired—and often low energy persists throughout our entire day.