Sleep stage transitions, ultradian cycles (& 3am wakeups)

The science behind difficulty falling asleep vs. trouble staying During sleep, your brain cycles through 80- to 120-minute ultradian cycles. At the end of each cycle—and during transitions between sleep stages—the brain has brief arousals on the order of seconds to minutes. Many of these aren’t remembered. It is during these moments that you become vulnerable to triggers that can turn a brief,…