Sleep’s Role in Obesity, Schizophrenia, Diabetes…Everything

Scientific American    Is sleep good for everything? Scientists hate giving unqualified answers. But the more sleep researchers look, the more the answer seems to be tending toward a resounding affirmative.

The slumbering brain plays an essential role in learning and memory, one of the findings that sleep researchers have reinforced repeatedly in recent years. But that’s not all. There’s a growing recognition that sleep appears to be involved in regulating basic metabolic processes and even in mental health. Robert Stickgold, a leading sleep researcher based at Harvard Medical School, gives a précis here of the current state of sommeil as it relates to memory, schizophrenia, depression, diabetes—and he even explains what naps are good for. [...]
So what is sleep for? Memories are processed during sleep. But sleep doesn’t have just one function. It’s a little bit like listening to tongue researchers arguing about whether the function of the tongue has to do with taste or speech. And you want to say: ‘Guys, c’mon, it’s both.’ There’s very good evidence now that sleep, besides helping memory, has a role in immune and endocrine functions. There’s a lot of talk about to what extent the obesity epidemic is actually a consequence of too little sleep. [...]

What are implications of sleep for psychiatric disorders?
If you take an adult who has both sleep apnea and depression, you’ll find that they are very tightly linked. If you have depression, there’s a fourfold increase in your likelihood of apnea and if you have apnea, there’s a fivefold increase risk of depression. If you take someone with both depression and apnea, and treat the apnea with CPAP [continuous positive airway pressure], you can get their depression scores to drop below clinical levels.

If you take kids comorbid for sleep apnea and ADHD—in the case of children the apnea is usually caused by enlarged adenoids and tonsils—if you remove the tonsils and adenoids you’ll get a larger reduction in the ADHD symptoms than if put them on Ritalin.

If you take people with bipolar disorder and sleep deprive them, you’ll flip them into the manic state.

If you look at depressed people, REM sleep comes much earlier in night. When treatments for depression fail to reverse this effect, the likelihood of recurrence of the depression is much higher.  And depriving depressed patients selectively of REM sleep can produce a dramatic reduction in their symptoms, although they return as soon as the deprivation is stopped . [...]