To get the most from your first cup of coffee, you must drink it between 9.30am and 11.30am.
Steve Miller, a PhD student in the US has discovered that the there are many factors that can change the impact of caffeine on your body and as your body is producing its own natural alertness between 8am and 9am, so it doesn't need any help from coffee during that, Stuff.co.nz reported.
However, as your body comes down from that cortisol peak, a coffee will keep your alertness high, making it important to carefully time caffeine intake.