Do you get eight hours of sleep a night but don’t wake up feeling refreshed? It could be that the quality of your sleep is to blame, according to an article on CNET.

Sleep is divided into REM sleep and three stages of non-REM sleep. (Rapid eye movement (REM) sleep is a stage of sleep associated with dreaming and memory consolidation).

All are essential to feeling well rested. Deep sleep, the final stage before entering REM, boosts recovery and growth. Heart rate and breathing slow, and muscles relax.

As a person cycles through sleep stages throughout the night, they get the longest stretch of deep sleep during the first half of the night. The segments shorten with each cycle. People typically spend 13% to 23% of their rest time in deep sleep.

If sleep cycles are disrupted — whether by loud noises, a crying baby or sleep apnea — the quality suffers. How can you tell if you’re not getting quality sleep? Some tell-tale signs include:

• Waking up exhausted
• Irritability
• Poor concentration
• Difficulty with memory
• Taking more naps than usual

Source: Nightcap/Bedtimes Magazine