For Sleep Specialist Dr Jade Wu, when you sleep is just as important as how much you sleep.

“You’ve heard of people being night owls or morning larks, that’s not just someone’s preference. That’s biological. We are hardwired to be sleeping at certain times,” Dr. Wu told Nick VinZant during an episode of the Profoundly Pointless podcast.

A board-certified sleep psychologist and sleep researcher at Duke University, Dr. Wu says everyone’s body operates according to their circadian rhythm, a 24-hour clock that tells the body when to sleep and when to wake up.

Dr. Wu says the real secret to a good night’s sleep, isn’t getting eight hours of sleep. It’s getting eight hours of sleep at the right time.

“For example, I need eight hours of sleep. And if I get it between midnight and 8am, I feel absolutely great. However, if I get the same eight hours between 10pm and 6am, I feel like total crap for the whole day. So, if you’re getting eight hours and don’t feel good, maybe you need to sleep at a different time,” said Dr. Wu.

Dr. Wu says our phones and other digital devices have wrecked havoc on our sleep cycles by impacting our suprachiasmatic nucleus, a small part of the brain that regulates our circadian rhythym.

“The suprachiasmatic nucleus (SCN) is the body’s master clock and it knows what time it is based on how much light is coming in. For our ancestors, when it was dark it was night and when it was light it was day, so they had a very clear way of telling what time it was. But now, we’re watching TV, we’re on our phones, we’re working inside and so we are completely messing up the brain’s ability to tell what time it is,” said Dr. Wu.

Dr. Wu says the best way to get around this is to limit screen time before bed, set your devices to night mode or wear blue light glasses.

To hear more of Dr. Wu’s tips for a good night’s sleep, check out this episode of the Profoundly Pointless podcast. We talk her nightly routine, wake up tips and why we don’t die in dreams.