Why Does Sleeping In Just Make Us More Tired?
This post originally appeared at Wired.
We’ve all been there: It’s been a long week at work, so Friday night, you reward yourself by going to bed early and sleeping in. But when you wake up the next morning (or afternoon), light scathes your eyes, and your limbs feel like they’re filled with sand. Your brain is still lying down and you even have a faint headache. If too little sleep is a problem, then why is extra sleep a terrible solution?
Oversleeping feels so much like a hangover that scientists call it sleep drunkenness. But, unlike the brute force neurological damage caused by alcohol, your misguided attempt to stock up on rest makes you feel sluggish by confusing the part of your brain that controls your body’s daily cycle.
Your internal rhythms are set by your circadian pacemaker, a group of cells clustered in the hypothalamus, a primitive little part of the brain that also controls hunger, thirst and sweat. Primarily triggered by light signals from your eye, the pacemaker figures out when it’s morning and sends out chemical messages keeping the rest of the cells in your body on the same clock.
Scientists believe that the pacemaker evolved to tell the cells in our bodies how to regulate their energy on a daily basis. When you sleep too much, you’re throwing off that biological clock, and it starts telling the cells a different story than what they’re actually experiencing, inducing a sense of fatigue. You might be crawling out of bed at 11am, but your cells started using their energy cycle at 7. This is similar to how jet lag works.
But oversleep isn’t just going to ruin your Saturday hike. If you’re oversleeping on the regular, you could be putting yourself at risk for diabetes, heart disease and obesity. Harvard’s massive Nurses Health Study found that people who slept 9 to 11 hours a night developed memory problems and were more likely to develop heart disease than people who slept a solid eight. (Undersleepers are at an even bigger risk.) Other studies have linked oversleep to diabetes, obesity and even early death.
Check out the full story at Wired.