The reason some people experience sleep inertia while others don’t relate to where someone is in their sleep cycle when they need to get up. Junge says early birds have their deepest sleep a few hours before the sun rises and are therefore in a light sleep stage when their alarm goes off. That means they can then easily transition to wakefulness, which is why they feel “really quite light” when they rise.
Night owls, on the other hand, are more likely to be in a deeper sleep cycle when their alarm rings. Yanking yourself out of a deep sleep cycle and being thrust into wakefulness isn’t easy, Junge says, which is why night owls can start the day feeling worse for wear.
But sleep inertia doesn’t just affect night owls. It can also rear its head when waking from an afternoon siesta. In fact, Junge says it’s the reason people are advised to limit themselves to 15-minute power naps. Snoozing longer makes you more likely to slip into a deep sleep cycle, leaving you more sluggish than when you dozed off.
Sleep inertia doesn’t just affect night owls. It can also rear its head when waking from an afternoon siesta.
If night owls simply followed their natural rhythm (going to bed late and sleeping in), they’d have no issues with sleep inertia. But Junge acknowledges that this is not always feasible.
Instead, she says, starting the day with exposure to natural light can kick start your level of alertness. Coffee helps, too. Moving your body, especially outdoors, can also do wonders.
Movement does the trick for Jane, which is why she heads to gym first thing. Getting there is a slog, she admits, so she often sleeps in her gym gear to skip an extra step in the morning.
As for me, I heavily rely on caffeine on the days I’m struggling with sleep inertia. And on the days I follow my natural sleep rhythm – going to bed late, followed by a good sleep-in – I usually don’t have sleep inertia at all. Instead, I savor how good it feels to practically bounce out of bed, ready to take on the world.
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