Ask the Doctors: Sleep inertia can cause persistent grogginess, but lifestyle changes can help

Dear doctors: I recently heard about something called sleep inertia. It came up in a conversation about how to get a better night’s sleep. Is this real? I often don’t feel refreshed when I wake up and wonder if sleep inertia might be why.

Dear reader: Sleep inertia sounds like one of the health memes that trend on social media, but it is a real thing.

It refers to the persistent grogginess that sometimes occurs upon awakening. It’s a temporary state and typically subsides within 30 minutes or so. Sometimes, though, it can take a few hours to shake off.

Someone with sleep inertia wakes up feeling thick, fuzzy and out of sync.

The intensity and duration of symptoms can vary. It is known to be more pronounced among night-shift workers, teenagers and people who already have a significant sleep debt.

The reasons behind this transitional state aren’t fully understood.

Brain scans of people experiencing it show that some features associated with sleep persist despite the person being awake. An important factor in the likelihood of it occurring and the intensity is a person’s sleep stage at the time of awakening.

Sleep inertia is far more likely when someone is suddenly yanked out of slow-wave sleep — the deep and restorative phase of the sleep cycle. If your alarm clock goes off while you’re in light sleep, the transition to wakefulness usually is smoother.

Fluctuations in core body temperature are part of the nightly sleep cycle. Sleep inertia tends to be more intense when waking coincides with lowest point of that temperature shift. Other contributing factors include being out of sync with your circadian cycle, having an underlying medical condition and using certain medications.

Sleep inertia can impair thinking and decision-making, adversely affect learning and short-term memory and lead to slower reaction time.

Research has found certain strategies can help:

• For people who nap, keep it to maybe 10 to 15 minutes. Longer naps risk having you wake in the deeper part of the sleep cycle.
• Bright light suppresses melatonin, the sleep hormone. Exposure to bright light upon awakening can speed recovery from extended sleep inertia. The same effect isn’t seen in briefer episodes.
• Caffeine has been shown to shorten recovery time.
• A consistent bedtime and waking time are important.
• There’s also evidence repeated use of the snooze button to prolong sleep can bring on sleep inertia.

If morning grogginess persists and interferes with quality of life, talk to your doctor.

Dr. Eve Glazier and Dr. Elizabeth Ko are UCLA Health internists.