-Furthermore, many \gls{IOT} devices operate on batteries and higher energy consumption increases the amount of e-waste as \gls{IOT} edge devices are often hard to reach and consequently hard to replace \citep{nizetic_internet_2020}.
-
-To reduce the power consumption of an \gls{IOT} device, the specialized low-power sleep modes of the microprocessors can be leveraged.
-Different sleep modes achieve different power reductions because of their different run time characteristics.
-These specifics range from disabling or suspending WiFi; stopping powering (parts) of the \gls{RAM}; disabling peripherals; or even turning off the processor completely, requiring an external signal to wake up again.
-Determining when exactly and for how long it is possible to sleep is expensive in the general case and often requires annotations in the source code, a real-time operating system or a handcrafted scheduler.
+Furthermore, many of these devices operate on batteries and higher energy consumption increases the amount of e-waste as \gls{IOT} edge devices are often hard to reach and consequently hard to replace \citep{nizetic_internet_2020}.
+It is therefore crucial to lower their energy consumption.
+
+To reduce the power consumption of an \gls{IOT} edge device, the specialised low-power sleep modes of the microprocessors can be leveraged.
+Different sleep mode achieve different power reductions because of their run time characteristics.
+These specifics range from disabling or suspending the \gls{WIFI} radio; stop powering (parts) of the \gls{RAM}; disabling peripherals; or even turning off the processor completely, requiring an external signal to wake up again.
+Determining exactly when, and for how long it is safe to sleep is expensive in the general case.
+In practise, it means that either annotations in the source code, a \gls{RTOS}, or a scheduler is required.
+
+\Cref{tbl:top_sleep} shows the properties and current consumption of two commonly used microcontrollers in their various sleep modes.
+It uncovers that switching the \gls{WIFI} radio off yields the biggest energy saving.
+In most \gls{IOT} applications, we need \gls{WIFI} for communications.
+It is fine to switch it off when not communicating, but after switching it on, the \gls{WIFI} protocol needs to transmit a number of messages to re-establish the connection.
+This implies that it is only worthwhile to switch the radio off when this can be done for some time.
+The details vary per system and situation.
+As a rule of thumb, derived from experimentation, it is only worthwhile to switch the \gls{WIFI} off when it is not needed for at least some tens of seconds.