![Graphic showing raised beat rate during physical activity during the day, and lower beat rate during rest in the night. Heart clocks regulate the daily variation in heart rate – Each heart cell has a clock that regulates the frequency of firing rate between day and night. This helps the heart to beat faster during the day and to sustain daily activities.](https://www2.mrc-lmb.cam.ac.uk/wordpress/wp-content/uploads/Day_Night-heartrate-copyright_MRCLMB-150x150.jpg)
Alessandra Stangherlin (O’Neill group) found a cellular mechanism that facilitates daily changes in heart rate. ~24h rhythms in Na/K/Cl levels osmotically compensate for daily changes in macromolecular crowding to modulate cardiac electrical activity, in vitro and in vivo.