Unveiling the "Sleep" Secrets of Plants

Do plants really sleep? 😴🌿 It's called nyctitropism, or "sleep movements," and it's a fascinating phenomenon. Let's explore why some plants dramatically change their posture from dusk till dawn.

Why do they do it? The primary reason for these movements is to protect the leaves' upper surfaces from the cold of the night^[1]. Experiments show leaves that can't 'sleep' collect more dew, meaning they get much colder^[1].

Example 1: The Wood-Sorrel. During the day, its three leaflets are spread out flat. But in the evening, each one gradually falls until its underside nearly touches the footstalk, where it remains all night^[1].

Example 2: The Clover. Unlike the wood-sorrel, clover leaflets don't droop down. Instead, they rise up and fold over each other, exposing their undersides^[1]. The terminal leaflet even bends over to form a kind of roof for the others^[1].

It's not just a morning and evening affair. Plants that sleep are actually in constant motion. They continue to move throughout the entire 24-hour period, though the movements are quickest when they are 'going to sleep' and 'waking up'^[1].