Large-scale brain functional modularity is reflected in slow electroencephalographic rhythms across the human non-rapid eye movement sleep cycle

► Functional network modularity is increased during deep (but not light) sleep. ► Intermodular connectivity decreases with increased delta power and vice versa. ► Permutation tests on module membership reveal altered modules during sleep. ► Analysis of group-averaged networks reveals re-shaping of modules during sleep. ► Network cartography shows regions changing their functional roles during sleep.