How much sleep do you need?

Last week, the Wall Street Journal published an article about a small segment of society that seems to sleep very little - and perform perfectly fine, if not above average. In fact, most of the individuals interviewed were successful executives and business owners. Why is it that these people seem to need less sleep than the recommended 7-9h per night?

A few research groups have tried to address this question. Data from a lab at Harvard suggests that 'short sleepers' who get less than 6h of sleep per night are chronically sleep deprived, but somehow able to tolerate sleep pressure better than others. Interestingly, when the 24h melatonin rhythms of long and short sleepers were compared, it was found that short sleepers have a shorter biological night. That is, the rise and fall of melatonin from sleep onset to wake happens on a shorter time scale. This suggests that their biological rhythms may have shifted to their sleeping pattern.

However, researchers at UCSF believe that short sleepers can actually fulfill their sleep need in only 4-6h (which is the focus of the WSJ article). Whether they actually need less sleep or are simply insensitive to sleep pressure, genes are expected to play a role. (Perhaps both exist, influenced by different genes.)



There are many people out there who think they are short sleepers, but the majority are not. Instead, they habitually sleep less and live in a perpetually sleep-deprived state, but often play catch-up on the weekends. Possessing an insensitivity to sleep pressure may seem great for productivity, but in the long run these people may be putting themselves at risk for the many negative effects of chronic sleep deprivation.

Sources:
Aeschbach et al. Amer J Phys 270, 1996.
Aeschbach et al. Sleep 24, 2001.

Are you a short sleeper, or know someone who is? The lab at Brigham and Women's Hospital is looking for participants in their next study! Contact sleepresearch@partners.org if you think you may qualify.