As melatonin levels drop, falling asleep becomes harder and the body’s internal clock can gradually shift later — meaning the disruption compounds night after night, not just on evenings when you scroll until midnight.
Why melatonin matters for sleep
Melatonin is a hormone produced by the brain in response to darkness, acting as the body’s internal signal that it is time to sleep. Exposure to artificial light — particularly the blue-wavelength light from screens — can delay or suppress its release, effectively tricking the brain into staying alert. Sleep specialists consider this suppression one of the most direct physiological links between evening screen use and poor sleep.
Even a silent phone breaks deep sleep and REM cycles
The problem does not disappear when you put the phone down. Even without active use, a device left nearby creates opportunities for interruption: a vibration, a notification light, or simply the impulse to check the screen after stirring awake.
Each of these micro-interruptions can break the natural sleep cycle, reducing the time spent in deep sleep and REM sleep — the two stages that sleep specialists identify as essential for memory consolidation, emotional regulation and physical recovery.
Over time, this kind of fragmented rest accumulates into chronic sleep deprivation, which has been linked to reduced concentration, lower productivity, mood changes and weakened immunity, as well as an increased risk of several long-term health conditions.
A 30-to-60-minute digital curfew before bed, the key recommendation
Sleep experts recommend setting a digital curfew — stopping phone use 30 to 60 minutes before going to bed. This window gives the brain time to wind down and allows melatonin production to resume at its natural pace.
