Missing out on precious hours of sleep is exhausting, no matter how you slice it — but if you’ve noticed that you feel even more tired when your sleep is interrupted, there’s science to back that up.

“We awaken 30 to 40 times every night normally,” W. Chris Winter, MD, a sleep specialist at Charlottesville Neurology and Sleep Medicine and author of The Sleep Solution: Why Your Sleep Is Broken and How To Fix It, told POPSUGAR. However, these aren’t conscious awakenings.

If you instead wake up for long periods and struggle to fall back asleep, you can climb out of bed the next morning feeling physically and mentally drained. In fact, in a 2015 study, people whose sleep was interrupted reported a 31 percent reduction in positive mood — more than twice the reduction reported by those who slept the same amount in longer stretches. This is largely due to your body missing out on crucial deep, restorative sleep rhythms throughout the night, especially REM sleep.

One remedy could be a short nap. “If you’re wakened during the night by a fire alarm in your apartment and a subsequent hour-long evacuation, maybe a brief nap or rest period in the late morning would be helpful,” Dr. Winter said, noting that 20 to 30 minutes should suffice. However, he warned against frequent naps. “Watch out for napping as a ‘recovery’ for fragmented nocturnal sleep. Over time this can worsen the problem,” Dr. Winter explained. “If you wake up at night and you nap, you’ll have less drive to sleep at night, which can lead to more awakenings that can lead to more stress about it, longer naps, sleepless nights, and so on.”

Remember too that waking up often in the middle of the night could be a sign of sleep apnea or another sleep issue. “If the problem is persistent or worsening, you are the ideal person for a sleep evaluation or sleep study,” Dr. Winter said. “They are often exceptionally helpful in figuring out why you keep waking up.”