If you aren't asleep or settling into sleep by the end of your sleep window, your body will produce more cortisol to help you cope. It's a cortisol rush or a cortisol spike.
It actually kills brain cells so you want to avoid it as much as you can. To give your baby the most brain health potential, catch their sleep windows and help them keep to low stress. Be responsive.
For an adult, the late night second wind you get is a cortisol rush. Have you ever stayed up late, at a party or working and pushed through the tired feeling. Then you get your second wind. An hour or so later you may push through it again and get another second wind. Then by the time you do go to bed, you feel wired and tired? Then you sleep fitfully and wake early. Perhaps you feel sick in the morning. That's how babies feel when they get overtired.
It takes about 45 min to burn off the initial cortisol rush and then it has a residual effect, affecting future sleep so it messes with night sleep even if it happens during the day. The first step to improving sleep is to catch the sleep windows and maximize day sleep.
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