Sleep is the Swiss army knife of health. When sleep is deficient there is sickness and disease. And when sleep is abundant, there is vitality and health.
People often increase how long they sleep for over the weekend in an attempt to recover from sleep loss incurred during the week.
However, catching up on sleep doesn’t reverse damage to the body caused by sleep deprivation; rather, “recovery sleep” may make some things worse.
The Sleep Council says those between 18 and 65 need between seven and nine hours sleep a day.
When we first fall asleep we enter non-rapid eye movement sleep (NREM). This is divided into three stages, with each becoming progressively deeper:
Each sleep cycle lasts around one and a half hours and, in order to feel fully rested and refreshed when we wake up, we must experience all four stages. A full night’s sleep will include of five or six cycles, while a disturbed, restless night consists of fewer.
Ideally, our circadian rhythm will climb in the morning and make us feel alert and refreshed. It then peaks in the evening, and after being awake for around 15 hours, we will feel the pressure to sleep again. As the night draws in, our circadian rhythm drops to its lowest level, and we are able to close our eyes and fall asleep.
A new study "Ad libitum Weekend Recovery Sleep Fails to Prevent Metabolic Dysregulation during a Repeating Pattern of Insufficient Sleep and Weekend Recovery Sleep" looked at three groups of people to understand if recovery sleep is a healthy way of catching up.
Group 1 slept up to nine hours a night.
Group 2 was allowed a maximum of five hours of sleep a night.
Group 3 was allowed a maximum of five hours a night for five days, but were then allowed to sleep in for two days. They then had two more days of sleep deprivation.
Those who had only five hours of sleep a night gained about three pounds during the study. They also had a 13% decrease in insulin sensitivity, body’s ability to use insulin properly and control blood sugar levels.
Those who had "recovery sleep" gained about three pounds but had a 27% decrease in insulin sensitivity. Their natural body rhythms were also disrupted. They were more likely to wake up during the nights following the period of recovery sleep.
Clearly getting a proper sleep of between seven to nine hours a day is important, not only impacting on our wellbeing but our metabolism, weight and ability to regulate our blood sugar levels.