Glossary

sleep inertia

Sleep inertia is when you feel groggy after waking up suddenly, such as when your alarm wakes you up. Symptoms include:

• Wanting to go back to sleep
• Being less alert
• Poor mood
• Slower reaction time
• Poorer short-term memory
• Taking longer to think, reason, remember, and learn

Sleep inertia usually lasts 15 to 30 minutes, with the symptoms slowly fading over time. It can happen after you’ve been asleep for 30 minutes or longer.

People with idiopathic hypersomnia often have severe sleep inertia, which is sometimes called sleep drunkenness. Their symptoms can last up to a few hours and can include automatic behaviors. People with severe sleep inertia may be very difficult to wake and may need multiple loud alarms.