Warning: Undefined array key "visitor_referer_type" in /var/www/vhosts/wordinf.com/core/app/libraries/Core.php on line 98 Daniel Levitin - A good rule of thumb is every couple...
A good rule of thumb is every couple of hours take fifteen minutes off. Naps are also very helpful, short naps. Even a ten or fifteen minute nap in the middle of the day can be the equivalent of an hour and a half of extra sleep the night before, and it can raise your effective IQ by ten points.