How much sleep you need
Adult sleep need clusters tightly around 7 to 9 hours. A small minority function well on less, though far more people believe they are in that group than actually are. The practical test is how you feel at mid-morning and mid-afternoon without caffeine propping you up.
Sleep is not a bank you settle at weekends. Five hours on weeknights and ten on Saturday leaves you with a shifted body clock and a rough Monday. Aim for a schedule that varies by less than about an hour night to night.
- Teens generally need 8 to 10 hours, with a naturally later body clock.
- Adults need 7 to 9, which does not drop meaningfully with age.
- Older adults still need roughly 7 to 8, often in a more fragmented pattern.
What poor sleep costs you
Regularly sleeping under about seven hours is associated with higher rates of high blood pressure, type 2 diabetes, obesity, depression, and cardiovascular disease. These are associations rather than proof of causation for each outcome, but the pattern is consistent and the mechanisms are plausible.
Short-term experiments are more direct. A few nights of restricted sleep reduce insulin sensitivity, raise appetite-driving signals, shift food choices toward calorie-dense options, and blunt immune responses. Attention and reaction time degrade in ways people reliably underestimate in themselves.
- Metabolic — lower insulin sensitivity and increased hunger.
- Cardiovascular — the normal overnight blood pressure dip is blunted.
- Mood — sleep loss and depression reinforce each other in both directions.
- Safety — drowsy driving impairs performance comparably to alcohol.
Building better sleep habits
Your body clock is set mainly by light, and secondarily by meal and activity timing. That gives you two strong levers: a fixed wake time seven days a week, and morning light within an hour of waking.
In the evening, dimmer and warmer light for the last hour or two helps more than a strict device ban — what you are doing usually matters more than the screen itself.
- Keep the bedroom cool, dark, and quiet.
- Move your caffeine cutoff to eight hours before bed and test it for two weeks.
- Treat alcohol as something that costs sleep quality even when it speeds sleep onset.
- Finish large meals two to three hours before bed if reflux is an issue.
- Keep the bed for sleep and sex only, not work or scrolling.
When sleep problems need attention
Lying awake frustrated trains the brain to associate the bed with wakefulness. Get up after about 20 minutes, do something quiet and dim, and return when sleepy. For chronic insomnia, cognitive behavioural therapy for insomnia is the recommended first-line treatment ahead of medication, and its benefits tend to last after treatment ends.
Some patterns are not habit problems. Loud habitual snoring, witnessed breathing pauses, gasping awakenings, morning headaches, and heavy daytime sleepiness despite adequate time in bed are the picture most commonly evaluated for obstructive sleep apnea — common, often undiagnosed, and treatable.
- Bring two weeks of a simple sleep log to the appointment.
- Ask a bed partner what they notice; snoring is invisible to the sleeper.
- List every medication and supplement, since several affect sleep.
- Ask about CBT-I by name if problems have lasted more than three months.