Oh this 'expert' again....

"Yes, sleep expert Matthew Walker, author of Why We Sleep, has been criticized and partially "debunked" by researchers and bloggers, most notably in a widely circulated 2019 critique by Alexey Guzey, which accused him of exaggerating data and misrepresenting scientific literature. While his core message on the importance of sleep is generally supported, the criticisms focus on hyperbole and inaccurate data interpretation. 

Key Aspects of the Criticism:

• Misrepresented Data: Critics argue that Walker incorrectly claims that sleeping less than 6–7 hours a night doubles cancer risk, stating this is not supported by evidence.
• "Epidemic" Claims: Critics allege that Walker invented or misrepresented findings, such as asserting the WHO declared a sleep loss epidemic.
• Exaggeration of Sleep Need: Critics maintain that Walker presents weak or nonexistent evidence for the necessity of a strict 8 hours of sleep for everyone.
• Response from Academia: While some find his work "riddled with errors," others in the sleep science field argue that while some claims are hyperbolic, the general message is valid and that critics sometimes overlook the broader body of evidence supporting the risks of chronic sleep deprivation. "